As a mother of 4, I can whole heartedly say that if you feel like you are too young or that you aren't ready, then you are too young. And that is okay! Nothing says you have to be ready by a certain point or not.
I do think that having a child over the age of 40, while still good, increases the chances of your child having a genetic abnormality, specifically down's syndrome. Because of this, your doctor and the hospital consider you high risk, so you have to go into the doctors office a lot more frequently and do a lot more scans to keep a close eye on what is happening. Statistics show "advanced maternal age" increases the risks of many types of genetic issues that could be avoided otherwise.
But for the meantime, don't sweat it. You are so young and have so much life in front of you. When the time comes, you will know when you are ready for kids!