I have similar thing going on. I was never thin, but somehow I also think I don't realize how big I am?
I feel and look better now than I did 70 pounds ago. Or at least in my head I do. I have little moments where I realize the progress I've made like when I put my hand on my hip I can feel that there is less of me there.
I can put on an outfit and think I look completely fine, but then when I see pictures on FB or something I can't even look at them.