Okay, a lot of the sites I've been too have told me a lot about care for this kind of frog which is an Albino ACF. But I was wondering about sexing it. Should an ovipositor be visible already or would it develop more towards sexual maturity? From some pictures I believe mine is still a juvenile but there could be some malnutrition and general poor health issues going on from previous care. There are no black marks as of yet and there is a tiny little bump that could either be the ovipositor or just the end of his/her spine. My friend said it was female, but it's looking more like a male to me.

The poor baby is also very skinny, thinner than some of the pictures I've seen of young ACF's and the first thing they tried to do when I put them in the tank was eat a gold fish that was bigger that they are. I have since put the goldfish in a separate tank, they were both big enough to shake the frog off but got some torn fins for their troubles. Should I try feeding a little extra (like a few pellets) between the 2 - 3 day gap of a full feeding or get it on a regular feeding time instead?

Everything else is set to the best of my ability. I've got a 5 gal tank with a whisper filter, a terracotta pot to hide in, I'm getting some silk plants in about a week, I got frozen bloodworms from the previous owner but I also bought some Cichilid pellets. I might be getting a 10 gal tank depending on who drops what off at my manager's recycling center (she's seen some big tanks being sold off for $3, they'll rescue anything useful and sell it cheap at her location)

I also want to know if melafix is okay for this kind of frog. It's been my general purpose medical care for my fish but I want to know if I might be able to use it to treat any abrasions/tears/etc that the frog might get in the future that nature can't take care of on it's own.

Gosh that's kind of a lot. I'll give a rundown for anyone who tl;dr's me.
Sexing: Should I wait until it's reached adulthood to really tell or can I tell a female straight away?
Feeding: Can I supplement a little in the beginning (for say, a week) since the frog had poor care and appears underweight or should I just get it on a regular feeding schedule instead?
Medical: Melafix in emergencies. Yes or no?

Thanks for any help!