Texas Dominicans in General
Having lived here all of my life, minus a few years, Dominicans are all over the state of Texas. The reason that it's difficult to find most is because we don't go around broadcasting the fact that one is Dominican. It's one of those things that you just meet Dominicans through meeting people, and it will happen to come up in conversation.
Thus, don't fret. If you're here long enough you will come across the Dominicans. And once you meet one you will come across others. I live in Austin, but have met Dominicans in all of the big cities in Texas.
As far as liquor or cigars, you can find pretty much everything except Presidente. Brugal, Barcelo, Flor Dominicana cigars, etc., all of them are here. It's just a matter of finding where to get them.
And being that you are in San Antonio, you will always have Dominicans that are in the military. So they're there. Just give it some time.