well i know your situation exzactly i had been dancing since i was two and i stopped for 2 years to play soccer and when i got back it felt like i had completely forgotten everything and i had completely lost my flexibility but my advise to you on that is to stretch everyday 30 minutes a day doing every stretch that you would do in dance class it worked for me and i got my splits back and im able to do all my old things also dont focus on hurrying up and getting everything in your head just focus on doing good at your dancing and relearning and perfecting everything youll get there but you cant rush it or your dancing will turn out very sloppy.