1 week PP supply/supplementing problems

Danielle • Mommy to a precious little boy born 12/17/15 and full time working mom! I love my little family!
My son is a week old tomorrow (born 12/17). I have been exclusively pumping due to latching issues. He lost 1lb in 4 days because of his latching issues but I don't want to give up on giving him Breast milk. My milk came in two days ago but my supply isn't increasing even though I pump every 2-3 hours. I'm only getting about 1oz per Breast. I talked to a lactation consultant and she said its a normal amount for now but I feel like I can't keep up with what he's eating at this point. He's eating 2oz/feeding.
I've tried formula supplementing with 2 different formulas  (enfamil supplementing and enfamil gentlease). He projectile vomits with formula but not Breastmilk. We even keep him upright during and 30 min after formula feeds and he still vomits. 
Is there anything else I can do to increase supply at this point or another formula you recommend for supplementing in the meantime? I've read good things about good start gentle. Has anyone tried it?