Sandy,
I am a former TX resident who went through the name and gender change, without SRS/GRS, back in '10. I went through a lawyer here in TX that specializes in TS/TG legal stuffs, if you can afford her or need info on her please message me. I can only tell you what she told me. In TX, if you have your name changed first without a gender change it will be more difficult to go back for the gender change. Why? I'm unsure, TX is a messed up state and thus why I left. However, it IS possible to have the name and gender change done at the some time without having to have had SRS; which of course does not help in your case. I am from Austin/San Antonio and I have NEVER had a pleasant time going to the DPS; they are just unhappy jerks.