There's nothing illegal about 'dating.' If you are planning on engaging in sexual intimacy, you need to be sure to read your state's statutory rape/sexual assault statutes. Texas Penal Code Chapter 22 can be found here: http://www.statutes.legis.state.tx.us/Docs/PE/htm/PE.22.htm
As far as disrespecting her parents goes, it wouldn't really matter if the relationship were legal or not. If they don't want her daughter dating you, and you are aware of that but pursue the relationship anyway, regardless of what the statutes say, you are disrespecting her parents' wishes.
For informational purposes only and not to be relied upon as legal advice or for the formation of an attorney-client relationship.
Since she is younger than 17, then dating her is risky, as if you engage in sexual activity it is a criminal offense. In Texas it is an affirmative defense to prosecution, however, if you are within 3 years of her age. That three-year period is counted day-for-day, and I am aware of prosecutions in Collin County where a kid was charged when the difference amounted to only a few days. By your math, it appears that you are within this "Romeo/Juliet" safe zone, but be certain. Your comments indicate that you may have long-term feelings and want to have a good relationship with her family. Consider taking your cue from that, and respect their wishes, and restrict yourself to school and family gatherings.
The above answer does not create an attorney/client relationship. These responses are merely intended to provide general information about the question asked. Frequently, the question does not include important facts that, if known, could significantly change the answer. Information provided on this site should not be used as a substitute for competent legal advice from a licensed attorney in your community. The law changes frequently and varies from state to state. You should verify and confirm any information provided with an attorney licensed in your state