Honestly, IME, there is no way to tell them apart. Ive seen pairs together and you couldnt tell them apart. Not from the fins, head size, coloration or body shape, like you can with most cichlids.
I'm just going off the ones that I have had and the ones that I have seen around here. The females have a redder sheen and rounder fins. This is not the most reliable way to sex them. It's just my experience.
Im a big festae fan but i still think mayans are underappriciated, they can be quite beautiful fish.
as far as if its male or female, i have no clue but i do know he/she is looking a lot better and thats the important thing.
good job!!!