Some basics
Meet her family, Mom and Dad, that will tell you a lot about her. If they are poor, they have not been giving her money, so she told you a lie and is a player. If they are middle class you will know something about her background and how she was raised. Then tell her you want to see the bill from the University, so you can pay it directly. (My daughter goes to a university in Santiago and every time I see her, she shows me her grades and classes which are posted on line.) Many Dominican women study languages in order to only meet tourists, it does not mean she is in a university. I assume you are sleeping with this woman. If you are paying her rent and she has no roommate, drop in when you are not expected. She should be pleasantly surprised, if not you have a problem. Trust but verify. Many Dominican women have many "boy-friends" at the same time, especially if their boy-friends do not live here, they do a balancing act and get money from each of them.