Whoa, congrats! I didn't know you were pregnant again. That's wonderful :D it is a lot that's for sure!
One of the things that really helped us save a lot of money is using cloth diapers for the daytime. Yes it was a little gross washing them but for the first 8 months or so, it's just breast milk or formula poops so it washes out pretty easily lol. This kept the overnights as the only diapers and saved a lot!