Despite what we're taught to believe, men actually rarely make the first move. They generally only ask out women who've shown interest first by smiling, flirting, eye contact.
On some level, women know this, because men who DO make the first move, with unsolicited contact are usually rejected, shot down because they come across as "creepy."
I think as larger women, we're often taught to send out mixed signals (or no signals at all). When I was younger, I never wanted to appear "too interested" in a guy, for fear of rejection and humiliation.
I also think many guys who are attracted to larger women, or to women of varying sizes, sometimes tend to be a bit gunshy themselves about rejection, and they're doubly afraid of being shot down.
I met my husband through a personal ad I placed, at 375 lbs. My ad was confident, flirty and funny, and blunt about my size, my desired size and what I wanted in a partner and what I had to offer.
I got a lot more responses than I expected (though some were more than a bit odd, no odder than the guys my thin friends were dating).
I've always had better "luck" with men than my thinner friends, and I think that's because I've never compromised my standards. I was picky, bold, and confident (well that's not entirely true - I wasn't confident so much as I was better at faking confidence when I needed to).