I think I was born old. I had nothing in common with other teenagers when I was one and certainly didn't go partying or sitting in little groups chatting and that sort of thing. I thought I was a freak.
Now I'm relatively ancient I have found a few people I do have stuff in common with and have more choices in life.
I hope you will find the strength to engage in life and find your way as well as the odd daydream. It can be good to have a safe place in your mind to go to when stressed or sad, as long as you are in the real world too.
You will then have more facets to your life than other people. Most people can't talk to kindly characters in their imagination like you can. You can use them as a source of strength and comfort, or a hiding place.
I wish you all the best and for strength to face the future. It may have more good times than you think. Much of my life has been better at least in some ways than I imagined it at age 18.
Sending care and hugs!