In a United States Citizen and want to bring my girlfriend to the U.S. . She's from the Dominican Republic. And yes we want to get married

Congratulations. The fastest way to bring your girlfriend here would be through a K-1 fiancée visa. You can start the paperwork immediately, since you've already met her. The requirement is that in order to qualify to process a K-1 visa for her, you have to physically meet within two years of the filing date. You begin the process by filing the necessary forms and documents and paying the necessary filing fees and then waiting for the processing to be completed, which takes about seven months.