You are right...for many women, we see our weight as defining who we are. For many men, it is more of an "external" thing. Just a generalization...I know there are tons of exceptions.
I can say that for a period of time, what came between me and my husband was not my weight at all, but the way I felt about myself because of being heavier than I wanted to be. Eventually he put it out there and asked how I would feel if he constantly degraded himself the way I was doing...not very attractive. So body confidence is a thing I have been working on for a long time.
Also, people who struggle with weight see things a lot differently than people who have never had that problem. Here, you get a lot of folks who know exactly how you feel...but your athletic BF has no clue what it's like (no offense to him).
The "sexy" thread is a couple below this one...go to the Women's Only Corner main page and look down till you find it. It's several pages long and new folks are hopping in all the time.
And now that you don't have to be perfect, you can be good.