Well, there certainly is no rule that you MUST stop nursing at 20 months… but you probably will want to at least start weaning her within the next year.
Of course to wean a baby you keep giving them more and more foods other than breastmilk.
BUT if you are able to find ways to stay close and connected to her it will make it easier on her and you.
Here are a couple of ideas of how you can still have ‘bonding time’ with your baby when she is weaned…
1. cuddling before bed or at the time that you would usually nurse. You can hug her, tickle her, rock her, whatever.
2. look at picture books with her sitting on your lap and talk to her as you look.
3. You could have her sit on your lap while she eats baby food or whatever… but that could get messy
4. just come up with some creative ideas yourself. 🙂
Let us know how it goes, and remember that you don’t have to wean her just because everyone says you should (You just don’t want to end up with an older child that is still nursing 😉 ). 🙂