Randi makes some great points.
The whole "trans" thing can be really confusing.
Not sure I really understand much of it.
I am friends with a trans girl and she has had a really rough time with her family and their acceptance.
If this fantasy just popped up recently then maybe you should leave it a fantasy.
Just because you have a fantasy doesn't mean you have to act it out in real life.

Just know you can't please everyone and its futile to even try.
Please yourself and your spouse because thats really all that matters in the long run.

Thats true and don't get me wrong I struggled with confrontation and peer pressure growing up and was constantly bullied about being really skinny.
I have compassion for people that have confrontation issues but they need to understand its up to them to do something about it and not hide their feelings if people treat them harshly.
My Dad sat me down and explained that if I wanted things to change it was up to me to do it.
I learned to not pay attention to people saying mean things to me about how skinny I was.
Being a girl with basically a figure of a teen boy was the worst thing to have to deal with.

Just be honest and tell them stop if they always comment about your weight.
Generally good friends won't say anything to purposely hurt you but may mention you have gained a few pounds.
I don't understand why people these days won't stand up for themselves.
You don't tell other people how to live or they have to be slim do you?
Of course you don't.
Sure I had people tell me I was getting fat I just didn't acknowledge their comments.

You are very welcome.
Not often I comment but I know by experience that method worked for me.

I agree with Munchies.

I used to feel that way about how skinny I used to be.
Always felt awful about my body small boobs and no curves.
Now I love my body and feel 1000 times better about myself.
I'm not sure I would call it "confident" exactly maybe I stopped caring what everyone else thought.
I'm fat/ obese and that is what I want to be.
It makes me happy.

If you want to gain a lot you have to eat a lot.
No magic pill or food.
Heavy cream or ice cream before bed always made me gain.
Remember everyone is different so results will vary.
If you are real serious about gaining a lot you have to commit to it, not eat a lot for a week to 10 days expecting to gain a lot then be discouraged,
It takes time I mean months and years sometimes.

I absolutely do not like cold weather.
I keep a small heater under my desk at work because I get cold easy.
My BF is a big guy and he stays hot all the time.He wears shorts in the winter which is nuts to me.

Some people never get a double chin even if they gain weight.
I was like that for years a normal face with a fat body.
It sounds like you want to gain weight but have nobody notice. People will notice and you can't get around that.