Latching

My baby is 4 days old and is at the dreaded lost 10 percent of his body weight (😢).

We were having an issue with him

Latching/sucking in the hospital, so we stared using a breast shield.

He gets very frustrated and pushes away from the breast but once he's latched he does feed.

I went and saw a lactation specialist today and even though it looks like he's latching and eating, he barely ate anything. She suggested supplementing with 1 ounce of pumped milk in a bottle. We did that tonight after trying to feed and him and sucked the whole thing down no problem.

I am worried he won't want to breastfeed and will just want the bottle. I bought the size 0 nipple that is supposed to be similar to the breast.

Anyone have luck with an issue like this?