Yes. In Texas you are married if you are 18, agree to be married, live together, and hold out to the community that you are husband and wife.
This answer DOES NOT establish an attorney-client relationship. This answer is based on the limited information provided and is not intended to be conclusive advice. There are likely other factors that might influence or change the advice after a more lengthy consultation.
If you BOTH signed a declaration of informal marriage and filed it with the county clerk, then yes.
Or, you can have a commom law marriage as Ms. Lowry outlined for you. She has told you how to have a common law marriage.