I vote female as well. I don't see anything either.
To help you see what we're talking about, here's a male panther at 4 months. See the bulge we're talking about? In some males it isn't as developed at that age, but you can definitely tell it's there.
Female. Probably closer to 6-7 months instead of 3 months. Start reading up about sexual maturity and her first egg clutch. Enjoy the gram scale, sand and organic top soil...