You are correct that Massachusetts is not a member of the Drivers License Compact (DLC) but that Texas is. Though Massachusetts is not a member of this Compact they have agreements to exchange and receive information regarding traffic tickets with other states.

The MA Registry of Motor Vehicles (RMV) does not list which states they have agreements so when paying the speeding ticket ask the clerk of the court if he or she knows if the traffic offense conviction will be reported to the Texas Department of Safety (DPS). If points are assessed to your TX driver's license it is typically done by your home state Department of Motor Vehicles and not the out of state DMV.

According to the Texas Department of Public Safety they will place out of state offenses onto your TX driving record. The Texas points system lists that it is 2 points for a moving violation conviction in Texas or that in another state. Points however are not assigned for speeding less than 10% over the posted limit or for seat belt convictions.

As you mentioned both Massachusetts and Texas are members of the Non-Resident Violator Compact (NRVC). Being a part of this agreement means that your home state of TX should suspend your driver's license if you fail to pay, or otherwise take care of, your MA speeding ticket.