http://en.wikipedia.org/wiki/Ages_of_co ... rica#Texas
Quote:
Texas
The age of consent in Texas is 17 {Texas Penal Code Section 21.11}. However , "...It is an affirmative defense to prosecution under this section that the actor...was not more than three years older than the victim and of the opposite sex...(and) did not use duress, force, or a threat against the victim at the time of the offence" and is not a registered sex offender {Section 21.11(b)}.
Section 21.12 further prohibits all sexual contact between an educator and student enrolled at the primary or secondary school where said educator works. No age is specified by the statute (thus, even if the student has reached consent age of 17, it is still a violation), and violations are a second degree felony.
If you were precisely 3 years older than her you would be okay legally. But 18.5 -14 = 4.5 years.
In the state of Texas you would need a court order to be allowed to marry her at that age (and hence legally have a sexual relationship). If she was at least 16 you could marry her with her parents permission.