Im interested in this too as bub was put on formula due to weight loss but I still want to bf him.. Are u sure u have ur attatchment right? I've been told recently bub probably wasn't getting enough due to poor attatchment.. He would get on and suck for 20mins each side but still not appear full and this was because he wasn't getting enough milk but not because I didn't have enough milk if that makes sense.. Have u contacted the aba? They can be really helpful 1800 mum 2 mum they also might have some ideas for u on how to combine both and how to make sure bub is getting enough...