The Texas legislature changed the law effective September 1, 2017.
It's Section 2.101 of the Texas Family code and it's on-line for free.
The county clerk may not issue a marriage license if either applicant is under 18 years of age, unless each underage applicant shows that the applicant has been granted by this state or another state a court order removing the disabilities of minority of the applicant for general purposes.
Removal of disabilities is what emancipation is called in Texas. You must be 16 or 17 to even apply for it. AND judges usually won't grant it unless you are able to 100% support yourself without anyone else's assistance.
I find that most attorneys won't help a minor seek emancipation without at least $5,000 on account since it is not easy and there is a lot of work to be done to prove that a child is able to 100% support themselves without help from anyone. I find that only athletes and entertainers qualify - they need to be able to sign endorsement contracts. I don't see the regular teen-ager convince a judge to sign unless both parents agree to this lawsuit.
Chapter 31 of the Texas Family Code covers "Removal of Disabilities of Minority". It goes into detail under Section 31.002 of the minimum required info that the Petition must contain.
Section 31.004 requires the judge to appoint an amicus attorney or attorney ad litem to represent the interests of the petitioner (the child) at the hearing. You pay for this attorney and it normally costs at least $750 and can go up to $5,000 depending on their hourly rate and how much work they have to do.
If a judge signs the removal of disability paperwork then you take it to the county clerk who issues marriage licenses.
You will need a certified copy of the judge's court order. Generally a certified copy is approx. $1 per page. Clerks accept credit cards and cash. No checks.
So even with a parent's approval you cannot marry until you are 18.