I'm in my mid-50's and can tell you time flying by (and what you think you're not ready for) will be a life-time of experiences and revelations. This much I can tell you beyond the shadow of a doubt. Never compare your dreams with others. You work within in your framework and quit looking at the herd. The only person that has to live with your decisions is yourself, so plan them accordingly.
You've lived a pretty sheltered life based on your description, so you need to get out and experience the world. I was a late bloomer at 19, so I spent allot of my 20's going out and experiencing life and relationships in ways quite frankly I'm not all that fond of owning. But that is part of the maturing process and figuring out your boundaries of identity. I wouldn't be where I'm at today if I hadn't gone through all of that.
You also answered your own question regarding relationships and making families. You're not ready. That's it. Never trivialize what you know to be true within yourself. Committed relationships and having kids are for people who have already taken that journey and been to the world of "what -if" and spent their time figuring themselves out and living on the wild side. Because once you commit, you have to give less attention to yourself, especially where kids are involved.
When you have other people to account for, you can not be looking over your shoulder when times get tough and thinking, " I should have done something different." That time is now. So go out and explore the world and find out what you're made of and what you want to do. I guarantee you, you'll change direction at least ten times, if not more. What other people do is their own personal journey. That is not yours. Always make the distinction.