I think that your concern about not wanting to misrepresent yourself is laudable. But I also think that it's not justified in this case.
As several, most notably TinMan, have pointed out, BBW is a very vague label that may mean different things to different people. To me, it just means fat. As in over 40 BMI.
We can quibble all day over the best adjectives or adjectival phrases to describe your physique. But that is largely irrelevant
if you have a photo that accurately shows your body. And you do.
Personally, I'd say "built for comfort, not for speed," " thick, but not fat," "voluptuous," "full curves," "full figured," etc. are all in the ball park. But they may well suffer from the same problems that BBW does -- it may imply heavier, or not so heavy to certain folks. But honesty is the key, and the photo you post is not one of those "flattering" "let's hide the fat" bait and switch jobs. It's attractive, it's honest, and it allows each hobbyist to make up his own mind based on the closest we can get to objective evidence, not inherently ambiguous words.
On a personal note, I'm kind of a size snob and prefer thinner girls, but I'd do you!!