taste of your milk will change
milk may dry up/change to colostrum (you can keep nursing through this. that way you still keep the emotional and sucking needs met, and when your milk comes in after baby is born, your toddler goes back to getting all the benefits from the actual milk again)
your nipples may be sore
your uterus may contract during/right after feeding your toddler. it used to be thought that these contractions could cause miscairage or preterm labor. now it is know that they are just Braxton-Hicks type contractions, the same type that many women have after intimacy. they can be annoying, but are not harmful.
you will be insanely hungry
when your colostrum comes in your toddler may have soft or runny stools because it is a bit of a laxative, this is only an issue in that the diapers can become a pain
while you still have milk, you can somewhat keep your supply up by staying hydrated and eating well, but when/if it does dry up is hormonally controlled. and eat well, pay attention to what your body is asking for. for me, bananas and red meat have been a really important part of my diet, but what your body needs will probably be different than what my body needs. the big thing is to eat a lot, and eat often.