Well if you're looking to mix things up a bit, try taking some of the basic things common to the stories you've written so far and tweaking them, if a change can be accommodated that still meets your fetish.
So for example, both times, the girl blows up for others' entertainment. If you're open to it you could have her inflate in private, or in a scenario where others fear her.
Are you open to popping ideas which do not meet the round girl theme of your stories so far?