Texas Penal Code §22.011(e)(A) lays out a defense to subsection (a)(2), which makes it an offense to have sex with a child, and states, "it is an affirmative defense to prosecution [that] . . . the actor was not more than three years older than the victim and at the time of the offense." This is often referred to as the Romeo and Juliet rule, and so you guys are in the clear. I understand why the other attorneys who answered the question would tell you no out of an abundance of caution and to avoid the wrath of overzealous prosecutors motivated by an angry parent as is often the case in these situations, but according to the law, there is nothing illegal in Texas with the fact pattern you described, assuming all the ages and birthdays are exactly as you've stated. The only caveat is that this exception would not apply to you if you're already a sex offender, which I assume is not the case.