Yeah, me too... at this point, I'm really confident Butter is a female.. if I'm able to get her probed or popped by a vet for free or for a reasonable price, I will.... but after feeling around her vent, sides near the vent, and down her tail.. she doesn't have a bump like Peaches (my male) has near his vent.
I think because she's been alone for awhile, she didn't want to waste anytime and started courting him in hopes he'd lock up with her.