I suffer from the same thing so it's good to hear that I'm not alone. Back when I was a size 16 I would look in the mirror and think I looked great. I didn't think I looked fat at all. Now that I lost weight and am a 6/8 I think I look larger when I look in the mirror. I look fatter to myself now that I did 50+ pounds ago at my all time high... Something in my brain isn't right
I can tell the difference in pictures though. I'm not sure what it is about the mirror but because I avoid photos (at any size I hate having my photo taken) I think I let myself get a lot bigger than I would have had I seen the reality in pictures. That damn mirror and my brain were telling me I really hadn't gotten THAT big when clearly I had (let's just say I wore out the crotches of like 4 pairs of pants from my thighs rubbing together...).
It makes me feel a little better to know I'm not alone.