Is this why moms always look so frazzled?

This post is going to be a little disjointed, because that's how I feel. Now that Ben is 9 months, we've entered into a new phase of parenting. I remember when he was just a few months old thinking that it would be really hard once I had to start setting limits and making rules. I always thought I would be a really strict mom. I would always see people with their bratty kids at the grocery store or Target, and think that's not gonna be me! Now, I don't really need to worry about that yet, but I'm starting to realize it's a lot easier to talk about setting limits than to actually do it. 

Like all babies, Ben really likes to get into EVERYTHING. Some of it is ok, and some of it isn't, but how do you decide that? I mean, he really likes to rip up paper. So recently I've found myself letting him rip up random catalogs that I don't care about, but deterring him when he tries it with magazines or books. Of course that's probably not correct. Because he doesn't know the difference between those he needs to know he can't rip up anything, or else I just need to move them all out of the way. This is what I mean. I'm afraid I'm just going to be one of those moms that calmly looks on while their child destroys things. How did I get this way? How do you decide what battles to fight? I'm tired all the time, and that contributes to me just shrugging my shoulders and letting it go. He's also started biting all the time. He bites Joel and I on our necks or shoulders, or he crawls to my leg and chomps on it. I know it's just teething, but am I supposed to say, oh he's just teething, or am I supposed to say "no" and then redirect his attention?

 My brain feels so scattered. I leave Ben in the living room to play while I get laundry from the bedroom or something, and when I come back he's crying because he fell, or he's messing with something he shouldn't. But if I stay and play with him all the time, I feel guilty about not getting things done around the house. I can't take him with me everywhere! Maybe I should, though. Is that the secret? It gets old constantly re-directing his attention from the fireplace, or books, or the tv, or electrical cords, or the hot oven. Every time I break from what I'm doing to take care of him, I lose track of everything. My days just usually end up flying by in a haze of wondering around aimlessly and starting a million projects I can't finish. I miss my ADD medication, but I can't take it because I'm still nursing. I haven't felt this bad since elementary school. I remember going into my sixth grade classroom thinking "I WILL pay attention today. I WILL NOT look out the window. I'll try REALLY REALLY hard and listen to everything the teacher says." And I would try. I would clench my teeth and stare straight ahead. And then an hour would go by and I would suddenly wake up and realize I hadn't heard anything. And I would be so frustrated and feel like crying, and think, "why am I so dumb?" The past couple of weeks have been just like that. I get to the end of the day and think, "what happened? what is the matter with me?" I realize I sound really selfish and whiny as I write this. I don't know....I guess this is the part of parenting you can't learn from a book. Sometimes I miss the days where all I had to think about was eating and sleeping and changing diapers.