Originally Posted by teeneythebetta
... she also does the downwards posture that is says females are known to do more so than males...
I personally don't have much experience with female bettas specifically (yet anyway), but I do know that all the male bettas I've ever had do the downward posturing too. This is Draco when I had him in only a 1 gallon, from what I've seen it just all depends on the angle he's traveling when he sees his reflection:
Don't know if this has helped at all, hopefully a combination of information will help you determine for sure. Either way, still a pretty fish!