Breastfeeding frustration!

Summer

I am struggling to breastfeed my 3 week old baby! We started using a nipple shield in the hospital right after she was born. We began using it because baby girl had a severe tongue tie and my nipples are flat. We ended up getting her tongue tie snipped but still couldn't get her to latch without the shield. 

Now we are 3 weeks in and she has barely gained any weight (she is 1 oz over her birth weight and has been gaining only 2 oz a week). The Lactation specialist told me not to worry about trying to wean her off the nipple shield right away, but warned that she is not getting enough at each of my breastfeeding sessions. She wants me to pump 6x/day, feed on demand and supplement each breastfeeding session with 1oz of pumped milk. 

This has been extremely difficult to do because baby girl eats constantly and will only nap in my arms. How do I find the time to pump!! I feel like I need two more arms and extra boobs to make this all work! In addition to these issues, my milk supply has drastically decreased so I am trying to stay afloat. 

Anyone else out there having this much trouble? Its so distressing and I want to make sure baby girl gets what she needs!