If your daughter is eating a well balanced diet there is no need for milk. Milk is not a replacement for breastmilk/formula. The reason doctors recommend delaying introduction of milk is because it is a common allergen and early introduction can lead to increased sensitivities later on.
It sounds as if your daughter has cut back on her nursing, because you are in the later stages of your pregnancy. If you want to continue your breastfeeding relationship there is no reason to feel you need to stop now (or when the baby is born), but even if your daughter weans, just making sure she is getting a wide variety of foods will assure that she gets adequate nutrition. The best thing you can offer her to drink after breastmilk/formula is water. Juice is pretty much pure sugar (natural sugar, but sugar just the same) and milk is food for growing baby cows, so is completely optional for baby humans ;-)
Other drinks that people often over look are herb teas (mint, rosehip, chamomile etc), non-dairy milks (hemp, sesame, rice, etc), whole fruit blended into a thick juice (regular juice has all the fiber and goodies removed ie. my earlier comment about it being nearly pure sugar), lemon/lime water, coconut water, broths, etc. These are great options for keeping kids well hydrated--and also don't forget about fruit and veggies with lots of water like watermelon, tomatoes, oranges, and cucumbers.