Looking at your picture, I have a feeling it may be a Picta but, it could still also be a young female betta. If her colour starts to improve or her stripes start to show less, then it could be a female betta splenden or a male betta Picta. LOL
IMO she seems like a young female splenden unless you know its age.
Note: Check your bettas ventral fins, if they are short like Pictas are, more of a chance she is one.