You can still sign up for adult ballet classes. If there is a community dance company that does an annual Nutcracker find out which schools participate and take classes there. Eventually you may be able to perform with them, but I have to tell you you have romanticized the life of a "ballerina". It is not all spinning around on your toes in a pretty tutu in the spotlight. It's dam'd hard sweaty work, often painful, and requires giving much up, with absolutely no guarantees.
Sign up for teen/adult classes in the best ballet-focus school you can find and just see if the reality still speaks to you. Best case scenario, you will love it and it will become a rewarding hobby in itself.
Retired professional ballet dancer.