If guys are really open to dating bigger girls, why can't I get a date?

I'm 27 (F) and I'm beginning to think I'm just deluding myself. I am what you would call a bigger girl, size 16, very short at 4ft 10"" and yeah, I'm not very pretty and have no confidence but I'm just tired of feeling like it. I put myself out there to guys, I asked one out and I got told no because I'm not his type and I just don't understand what he meant. Like surely if he likes bigger girls he would have said yes right? I don't think guys really are open to dating bigger girls, they just want to use us to feel good. I have very low self esteem at the moment and I just feel useless. Any advice guys?