Betta Fish: Constipated, secretly a female?

Hey yall. So I was sold this betta as a “blue marble male”. Recently it’s had some minor floating issues, along w an enlarged stomach or possibly egg area? which I originally thought was a swim bladder issue, but maybe it could be constipation? The first photos are the days the betta was introduced to their new tank. On another note, I think he may be a lady. But I cannot tell. I am thinking this because of the smaller ventral fins, and shorter fins over all.