When do you know that you should stop breastfeed

I know there are mothers who breastfed their children up to 2 years of age. How did they do that? I mean, I believe, children at 2 years old should already have a full set of milk teeth. My baby at 8 mths old has only 2 teeth. And he bit my nipples few times before! And it was really damn painful though only 2 teeth. And my spontaneous reaction was? My palm laid on his buttock as fast as a fly flies away when I try to kill it! And his reaction was? 'Wa wa wa'..
Should I do something before disaster happens? Initially, I thought I would want to breastfeed him till he's 6 mths old. I've experienced once before when I want to stop breastfeeding. It wasn't a nice one. With engorged breasts, I have to endure the pain for more than a week. To breastfeed and to stop it too needs an iron determination. To relieve the pain, I just need to let my baby suck, that's it! But then, that will send signal to my brain that I still want my body to produce milk. And I know that we can find some medication over the counter to stop milk production immediately. But, it was not advisable to do so, as advised by the hospital's nursery staff when I called up to ask for help. Talking about the nursery staffs. They are very helpful. Any problems with your breastfeeding, breastpump, and baby, you just need to give them a call. And they will answer your questions without hesitation or grumbles. And sometimes, they will give you a long lecture.
Actually, when I told the staff that I want to stop breastfeeding, she was shock. She asked why. There are many reasons to defend myself. That I'm busy with work. That I can't get enough of rest. That I planned to breastfeed him for only 6 months. That my freezer has no more space to keep milk. Bear in mind, not just 1. It's 2 freezers! One in Cheras, and the other one in Subang. My mum complains to me everytime when she can't squeeze in her frozen meat in the freezer. Although my MIL never complained to me about her freezer storage, I still feel that I shouldn't occupied her freezer all by myself. And moreover, frozen milk has lifespan too. It's not like 10 or 20 years! By crook or by hood, I still need to use the frozen milk before it's expiry date. I can't just keep storing it. To search for breastmilk bag isn't that easy too. I have to travel here and there due to shortage. Till to date, I can only find 3 brands that are available here. And you won't be able to find 3 brands at the same place. And it's not cheap either. See? I have so many reasons.
But, I always give-in everytime when my baby starts looking for breast when I'm carrying him.