Starting BF at 6 weeks??

Hi all, so I had some issues with supply and baby not gaining weight in the beginning, and long story short I am looking to start breastfeeding at about 6 weeks postpartum. I offer baby the breast before he formula feeds (he has been formula fed since about 1 week postpartum), and purchased a pump yesterday (Medela pump in style). I am also on domperidone (sp?) as of two days ago to help increase my supply. I am pumping anywhere from a few spoonfuls to 1oz per session at this point. Looking for any advice you can give me as baby is not tolerating formula well due to a milk sensitivity. I have gone dairy free and also supplement with nutramigen....

Thanks in advance!