Is it possible that I can attend medical school in Puerto Rico after living there for three years?

I definitely think it's possible for you to learn Spanish. Once you're on the island you'll definitely learn it because you'll be completely immersed in Puerto Rican culture. You should look up on youtube sometime about all the Americans who study medicine in Cuba at ELAM and how they're Spanish was bad before they went to the island but they picked it up quickly. Besides, in Puerto Rico most of your clmates will know English, so you'll be at an even greater advantage than the med students in Cuba! The won't hesitate to help you out I'm sure. But I must warn you Puerto Rican Spanish is different from what they call "normal" Spanish. Sometimes it is spoken very fast. But once you get used to hearing Spanish in our accent you should be just fine! I'm Puerto Rican living in the US but plan on going next year to study. Good luck to you! Maybe I'll see you in med school!