Is my mom making me clean too much?

Doesn't sound too bad to me, especially since it's summer and I'm assuming you're home all day anyway. My brother and I always had to help clean and do chores. Heck, I'm 20 years old and I still help out around the house. It's just the responsible thing to do. And yes, our chore lists were about as long as yours during the summer months. Don't sweat it! Just have a positive attitude about it. Turn on some music, think positively, and you'll be done before you know it! :)