My 17 mth old pees too much in her sleep!?

She get changed right before bed..and doesnt really get too much liquid during the day. She has a bottle before bed...but not immediatley before or anything.she wakes up around 7or 8 most day and has a bottle of milk then with breakfast..and probably has another bottle of juice before lunch around 12...or 1. then probably another bottle or 2 before dinner around 5 or 6. then one before bed at around 8 or 8 or 9pm. But even when she gets changed right before bed she still has a diaper burtsting off of her when she wakes up and she sleeps through the night so i really dont want to wake up and wake her up just to change her..but we are ruining lots of sheets and making her crib smell...We'd like to start potty training her soon. She takes her diaper off alot at night too. But they say if they sleep through the night and are dry thats when they're ready...I just dont know lol. anyone know?? lol