I relate a lot to your post - that was me, too. I'm 21 and almost 3 months sober and have struggled with the same idea that I'm too young. And even getting sober at first, I didn't realize how much of my life was being affected by my drinking and how much it had changed my personality. And quickly. For me, I could not be happier with the AA fellowship, the majority of my homegroup is 10+ years older than me but they have accepted me and my story and my journey and I have become close with many of then.
Sure, I was only out for a short time and don't have as many war stories. But I know for a fact I would be dead if I hadn't gotten sober because my drinking had given way to mental insanity and depression and I didn't want to live anymore... but I still couldn't stop. Alcohol does not discriminate and it affects everyone differently and at different rates. It's easy to talk yourself around it being young, but you hit bottom when you stop digging. If you're done, you're done. Only you can make that call, but know you are not alone.
Best to you x