I am not an expert in these matters, but I have observed that Dominican girls from rich and promininent families get visitor visas quickly, and girls from poor families don't get them at all. Are you planning to bring your girlfriend in as a visitor or as an immigrant?
A student visa might be an alternative if she doesn't plan to work in the US. Marriage is another alternative.
Your government's concern is ending up with yet another illegal immigrant on their hands. Rich girls rarely go illegal, poor ones often do.
Your government will provide you with all the information you need, so don't pay a lot of money for immigration consultants who will charge those too lazy to get the info on their own. Unless you have extremely high level friends in the US government, and even then, you will probably have to go by the book.
Norman