I find there's lots of variance in what people think a BBW is...some think it's anything more than skinny, I'm a UK size 16 and often called a BBW on Adultwork but looking at the specific BBW cam sites, they are much bigger than me.
I'm not sure how it affects my camming...I make the most of my assets! Sometimes a guy will come into my room and say "at last, a real woman!" and that feels good. It's funny how some like me to show them my tummy when I normally try to hide it. Physically it may be easier to do some things if skinny but they guys are coming to see BBW for other reasons. I just do what feels right for me.
