I don't see how there can be such a thing as a normal number of partners at a given age. It depends on so many factors. How many relationships you've had, how long they've lasted, whether you have casual sex between committed relationships... how can there be a "normal"?

I certainly don't think you should feel bad about any number of partners, as long as you were doing what you wanted. Maybe you should examine why you feel bad. I know the only reason I felt bad about having had lots of partners was because it was kind of a testimony to years of sucking badly at relationships. So it wasn't about sex at all, but about difficulties connecting with people on a level beyond that.