Sorry guys, not really a question but what should I do next, was it a 1-time thing?

She is 24 and I'm 18. So we were sitting in the courtyard area and she brought out some beer and , she recently lost 25kg's, because she and her room mate go to the gym alot and wear those gorgeous tights. but anyway we were chatting and she invited me back inside her apartment to see her fishtank and then we started kissing and she pulled me on top of her than we had a great ride, I finished after like 4mins though. Than we returned back outside like nothing happened, except she was sitting on my lap and we were talking and flirting until I had to leave with my other cousins. I just got home and feel so good what do I do. btw its my 3rd time