Sometimes I feel this way and I also have 2 kids (7 and 8). I did not have the childhood and responsibility you did, and I commend you for it. You stepped up as a kid and did what parents need to do, bravo on you. I hope you and your sister are still close.
You are NEVER too old to figure out who you are. There is so much in life to do and experience. I've enjoyed life but after my brother died last year, who had severe PTSD and couldn't be around more than a few people at a time, I decided I would live my life for him and myself. I never pass up a concert. ALL my friends, family and colleagues know me as the music festival / concert goer. Music has helped me through all my trauma, pain and grief. So my favorite thing to do is see it live. I used to video call my brother, or send pictures and video while I was front and center. My husband and I are currently separating and I never felt like I lived my life like I wanted. It was never ever what I thought I deserved or what I expected, so I think I held resentment toward my seriously amazing and perfect husband. Due to my trauma I never felt good enough for him and that contributed a lot to our marrietal issues. Anyway, I've always wanted to see the world, it was my biggest desire forever. I'm getting my passport and going after my divorce. I haven't fully figured out who I am, at 32, but the fun part is, figuring it out as you go. We constantly grow and learn and develop and evolve. I'm not the person today I was in high school, nor will I ever be. I'm not the person I am today after all my experiences and repressed memories surfaced, I'm forever altered.
It's up to you to be happy in the moment and develop goals and then achieve them. I recently started drawing and learning the piano. I've always wanted to!
Jump in, head frickin first and be who you think you should be and be what you feel you deserve.
No one will hold your hand or guide you. IT'S UP TO YOU. Get it girl, you're obviously super strong, so instead of being strong for others, take a week and be strong for you. Good luck!