Hi there,
Well, assuming your Texas HL is legal,
he'll grow bigger, I read that they can reach up to
4 inches SVL. They need lots of ants, it sounds like it gets them, which is good.
They also need proper conditions to grow bigger.
If they're in a small container, consider moving them to a larger one. Like the Whiptaildude said, full spectrum lighting is in order. You can get these bulbs at almost all pet stores. You'd want one configured for desert lizards though.
Make sure there is enough room in your enclosure for it to get out of the heat though. To the issue of legality, If you don't have whatever permits you need to keep it legally, I don't know if you should release it.
You should probably give it to a wildlife official, because at least here in CA if you have a wild caught creature for over a month, its illegal to re-release them. Is it possible you have a really dark Round-tail? or maybe a Short-horned? As far as I know, those are still legal. I hope he will do well, though.
Ok well, there's my opinion.
Yours,
Phil