Of course not! We should all be free to experience our sexuality that way we think is best. You aren’t a prude at all for being strictly monogamous. I’ll go you one further. I wouldn’t even describe you as a prude if you had ended up finding out you didn’t really enjoy sex with your husband.
Some people don’t enjoy sex. And that’s OK!
You know what makes people prudes? Deciding that they way they value (or don’t value) sex is the way that other people should do.
Prudes like to force their ways of being and experiencing on others, because they can’t sufficiently imagine how different experiences can be valuable in different ways to different people.