How can I make him come back for more?

Many possibilities exist. Try being on top, men just LOVE that. Receiving oral can give you the best orgams second only to squirting if you have a man that knows a few things about "muffin-diving"(^_*). Doggie style is good too. You could try anal but that takes a lot of preparation in comparison to vaginal sex. Try going for longer periods of time, why stop with just one orgasm? Don't know how you feel about multiple partners at once but this could be an awesome experience. Finally, ther are some toys to try.

If you really are looking for something more pleasurable, try more romance. For example: Try a candlelight dinner at home listening to exotic cultural music with the lights turned down low. Afterwards, a full body massage with a skilled man(or recently learned) really gets your toes curled! The sky is the limit on this stuff.

I applaud your sexual security, with more women were like this. Too bad you are too young for me. Oh well. Do not be embarrassed, be confident and happy.