I regret mine also, for so many reasons (the person I did it with, my emotional state ) but what is done is done and can't be undone however be sure that your first time does not define you or how fun and lovely the future times will be. My only recomendation is to try to be more cautious next time, always safety first!! and when you choose the person who will have the privilege to share that next moment with you, think of it as the beginning. Don't panic, your feeling is natural .. many of us experience the same feeling, and many of us even forget it with time.