Before you go down the formula road, have you spoken to the ABA?
Give them a call, 1800 MUM2MUM, they are there 24/7 and have a chat to them.
There are many things you need to take into consideration, and many things you can do depending on what the actual issue is.

Generally, once you go down the top-up road, your supply will suffer, and ultimately, your BF relationship can be adversely effected.