What are you more afraid of losing him, or not getting to experience other people?
At your age, you’re not really that young anymore, and you’ve already been together for six years. But if you feel like things are moving too fast, you don’t necessarily have to break up, you can just slow things down instead. There’s no need to separate and go see other people.
Maybe the issue you’re having with sex can still be worked on together. Not everything has to be perfect. Based on your story, your boyfriend actually seems like a good partner.
But at the end of the day, it’s your choice what matters more to you. Are you going to focus on the negatives or the positives—and then work through the negatives together as a couple?