With mine, I am going to tank out the larger ones, and any ones who are chasing eachother. If you do take out a female, that is fine- just re introduce her to the tank with the others. It will probably be another little while before you will be able to tell.
When did you spawn yours? I have a journal of mine...pics, and info...
http://www.myfishtank.net/forum/betta-g ... post600164
Though, I don't think you can view the pics unless you are a member. I will need to find another way to post them here.