I so relate to that!! I start tapping my foot and rolling my eyes and making those "hurry the f up" hand gestures. My mom knows what it means, and she usually speeds things up and if she doesn't, I say "What's your point?" and she speeds it up even more.
Women like explaining things in detail and digressing too much. x.x

You should practice your patience, maybe learn how to zone out while she's digressing or whatever, but she needs to be aware of why you act like this as well and that it's nothing to get upset about. She sounds like a good mommy btw ^_^