General

I would ask if you are in a relationship now with a larger individual. Large people have been the butt of jokes for a long time. Love and respect is all you can do the rest is on them. It's really hard when they don't love them selves.
As for any new relationships use discretion case by case basis. Slow and steady.

I'd probably tell them about it if I been with them for a bit but never push it let stuff play out as it needs to

Have you ever discussed this with him?
Maybe he is just a considerate FA who is afraid to 'use' your fat because he is concerned that it might make you feel insecure. Websites like this may give a different impression, but (unfortunately) the vast majority of big women are not so comfortable with their body.
From what I have read from you also from previous accounts, I seem to remember that you sometimes go through such spells where you feel less comfortable with your size, and maybe he tries to not emphasize that by paying too much attention to your curves.
I am very much like that myself. With most of my girl friends I felt quite some inhibition to pay much attention to their bellies or other 'problem' areas that they don't like. Also the fear that they wouldn't 'get' how it arouses me and might think I'm a freak for loving their fat, has held me back quite a lot.
Unless I'm 100% sure that the woman I am with likes it, I will not go and grab rolls and rub bellies and tell her how beautiful her large hanging belly is.

This also fits with the fact that when he has had a few, he does grab your belly, because as we know, alcohol lowers such inhibitions.

I had just one so-so experience... befriended with some girl on local feederism site. Discovered she was kind-of FFA and also into furries art - killer combo for me. My first instant affection ever.
Some time later she told me she had boyfriend, but that didn't quite stopped me from visiting her in other city with a present she asked. Present was extra 12lbs weight on me (this is literally the only time I was able to gain some substantial weight on my own).
I met them both. Her boyfriend was least tall among 3 of us and I think he was weighting no more than this girl. But they were getting along so well that my affection quickly started to decay painfully. The end of that was as awful as it was good in the very beginning. She did start 2 dramas which pissed me off so bad that I dumped her both times, but then she would call back sobering and begging not leaving her because I was such a good friend and stuff. Both times that was very painful and 3rd was really the last. So I think her personality didn't agree with mine so to say.

I don't experience any sexual desire towards girls without knowing that they have FFA tendencies, but still I do feel lonely from time to time and trying speed dating occasionally. I usually have couple of girls who like me. Then if I start dating normally it usually lasts 3 datings tops - then everything just dies down. I dunno - maybe they feel absence of desire and affection... so I see they are losing interest and so do I... and then it ends.

I'm trying to find out any signs that girl might be inclined towards such fetish without asking directly (its still quite awkward for me), but usually it boils down to "it doesn't matter how you look - you're a nice person" and then just stops...

Now I want to just give up on that feederism thing - obviously it doesn't work and also impacts life and health, because endocrinologist discovered that I have mild insulin resistance, which explained my extra weight and sweet cravings. I was prescribed some pills to lower insulin and was recommended to go low-carb and I lost 4lbs in a week already. Hope to continue that way - at least numbers started moving in some direction

It is not easy, true.
But I would say, do what I have done:
Stay true to your own self! Don't do compromises, live out what is your real you.
I started off as a feeder, first time I fed a woman was the most wonderful experience ever. I learned, that sex was much more intense with a feedee, that could understand that I wanted her to grow, that I loved fat, wanted more fat.
Then it came home to me, I was starting to gain myself. Then a woman that had been my feedee confronted me and asked me if I was purposefully gaining. I admited it and she said that would love to fatten me up and see me grow. Something made click in me and I have been gaining ever since. I have discovered that I also love being fat, and next to helping women gain, I'm on the spot now myself. Not with that woman, that relationship did not work out, but every woman I met that was into this, I gained more. And now I'm on track to getting really super obese and I love it, I help it along, because I know it is my true self. I want a woman that loves my belly, appreciates it and wants me to grow for her. Having a partner that wishes that you expand is just heaven, and what has helped me is a woman showing me that she is into really very obese guys and showing me pictures and talking about why they like moobs or a really fat fupa. I guess I have been blessed, to have received a lot of encouragement from German female feeders, in the USA, female feeders are in almost all cases not really out about what they like and they hide themselves, which makes meeting them almost impossible. They don't stand by what they like, which is a damn shame. I don't know what that is, it might be that in the USA, people are much more repressed and less developed sexually. But I was always amazed, meeting female feeders online in Germany, how open they were, the admitted that it turned them on and it showed that they had pondered liking big guys for years and I did not have to educate them about it, they already knew.

See it this way: If you are a feeder or feedee, you will always be. Nothing will change that. So why not stand by it and admit it?
And seek out partners that are into it and avoid people that are not? What future does that have? Have you ever had sex with a feeder / feedee? Well, once you do, sex with a person not into it will become super boring and dull. Eventually you can't go back anymore, you can't get the junk food, you can only get the food you really like, to use an analogy.

And the true self always wins out, you can maybe delay it, have some more bad relationships, that won't go anywhere, but eventually, it will all come out and want to be heard. And by the way, you can also have a love relationship with a feeder / feedee, more so even, because you really really accept and understand eachother like never before with somebody else.

Oh, another important thing that has always worked for me:
Make sure you meet feeder / feedees in real life, whenever possible. This make sure they are real people, not just some online lurker, that is wasting your time. If you realize that they are deep in the closet, have no pictures or only 1, forget it, they will never meet you.
Once you meet them, you can start dating, meaning that you just get to know them as you would anybody else. BUT you will know they are into what you are into. Sadly, there is absolutely no real life community about feederism, people hide something pathetic and all my efforts to organize regular large meetings where people can get to know eachother have failed.
This would make things so much easier, having all people into this in a group. But you can still meet 1 on 1.