Molly,
I'm glad you have received so many wonderful responses - I enjoyed reading them and I think I learned some things as well!
My two cents worth - I used to subscribe to Psychology Today, but I discovered that it was more like Pop-Psychology Today! Everything was so over-simplified that I found it useless, even as an Intro Psych teacher. Scientific American Mind is much better.
Having said that, the basic definition of paraphilia is correct, but I think there has to be some indication that the paraphilia is preventing you from having sexually fulfilling relationships. We all have things that we "need" in a relationship both physically and emotionally. Your need is just more specific than most. It obviously sounds like you were connecting emotionally with at least some of your partners - you just need to find one who also likes to stuff!
What you need to think about is this: Let's say you find someone who you fall in love with who shares your desires to stuff. You develop a complete relationship (not just one based on the act of stuffing) and both of you are happy and fulfilled. Let's say at some point your partner can no longer stuff - they have gained more weight than is healthy or develop stomach problems. Would you then leave this person? This is the point that your fixation on stuffing would become a problem - if you could work something out that still got you off, then I would say it wasn't a disorder. If not, then finding some help might be in order.
Just a thought - would fantasizing about stuffing your partner be enough to get you off during "normal" sex, even if they weren't stuffed right then? If that works, then I would say you have a solution to your problem.
In my own journey, being male I don't usually have problems getting off - but what has gotten me there most efficiently has changed over the years. I was pretty much trapped in the standard slim, big boobs socially acceptable attractions, but at the same time I found pregnant women sexually interesting (though I have never been with a pregnant woman) but I didn't really see fat women as sexually attractive. Only about a year ago I came across some female water bloating vids and something about it just made me cum harder than I ever had! This led me to stuffing (I totally understand your attraction there - and even as a hetero male I was fascinated by that guy's belly in your link!) and after watching the results of the stuffing - namely lovely jiggling bellies, I came to appreciate large women as well.
However, this appreciation didn't fully develop until I came to accept my own belly. I love to stuff too - although I am fat and it just doesn't show as well! I have always been heavy and always assumed I would be happier skinny. With this acceptance of myself I have come to find a wide range of body styles attractive so all I need to do now is find someone compatible who appreciates my big belly!
I hope that makes sense / helps!