Is it legal for a 17 year old female to date a 22 year old female in Texas?

There are no dating laws in Texas, only laws concerning sex and sexual contact.

Under Texas law, for purposes of this section (22.011) a child is anyone under 17. So at 17 it is legal for a 99 your old to have sex with them. It was illegal to have homosexual contact in Texas. This was ruled unconstitutional under Lawrence v. Texas. So to answer, it is legal to date, and legal to have sex.