I've known these feelings--a combination of introversion, and then later ADHD for me. With too much noise and hubbub, sometimes I just can't think, you know? And the other thing that brings it on is low blood sugar.

You're doing well if you're able to keep from venting that frustration at your kids, and are letting them just BE kids. Just so long as they aren't shrieking That Note-- that has to be nipped in the bud!