I lived in Houston from 2009 - 2016. I have a lot of facebook friends in the trans community who are still in the area.
Last I was there, there were a couple of support groups. The first one was Monday evenings (around 7:00pm). It was at Grace Evangelical Lutheran Church right in the Montrose neighborhood at 2515 Waugh. This tends to be more of an older crowd.
The second one is on Wednesday nights around the same time, 7:00pm. It's at the Montrose Center at 401 Branard St. The crowd there tends to be younger and hipper, but there can be more drama from the people in this group.
I'm confident there are other social groups in the area, I've just lost touch with a lot of them. If you PM me your facebook profile, I'll be happy to introduce you to some local resources.