If you see a pond near-you that looks nice maybe around a newer looking ranch house or property...stop and inquire if they are happy with their pond and who built it. Most people love talking about their stuff.
Maybe try calling the Frio County AgriLife Extension office and see if they have any suggestions:
https://frio.agrilife.org/These boys not too far from you look like they may know how to build ponds, but I dont know anything about them. This quote on their website might indicate they would work on your smaller type project:
"We make ponds from one half acre to over 100 acres".
https://www.weberconstructionco.com/tanks.htm