Tired of being a second choice

i didn't really know where to post this but i hope i get some advice. it just seems to me that I'm always the girl that guys can talk to but never actually want to date. I blame it on my appearance because I'm not the smallest girl I am plus size but not overweight. It does take a toll om my self esteem when a crush I have chposes a friend over me. I guess I'm just lost as to what to do.