If her scales aren't pine coning it probably isn't dropsy. If it were dropsy she would also probably be swollen throughout her body instead of just her belly, and she would probably be looking pretty miserable. I've had a couple fish get dropsy, and it isn't a pretty sight. I've had quite a few Bettas look like yours does now, though, and it has always been a case of too much food leading to constipation and bloating. I had one male who would bloat up like that after almost every feeding and have swim bladder issues as well. I just had to be very careful about how much and how often I fed him. Just keep your water clean and keep her meals a little smaller and you shouldn't have any trouble getting her back to normal. The peas should help her recover faster. I just keep a bag of store brand frozen peas in my freezer at all times and I feed the peas fairly regularly to keep my fish's digestive systems in line.