Not gaining weight

Laura
My son was born 2/8 at 8lbs 7 oz.
He was jaundice. When we left hospital he was 7lbs 8 oz. His dr said he was up from when jaundice was first detected. We supplement in hospital and a day or so at home for jaundice but still nursed. 
At his appt few days later he was 7lbs 11 oz. 
dr wanted him back at his birth weight right before 2 weeks but he was 7lbs 8 oz. We were nursing and pumping.  He was having correct amount of wet diapers. Dr says he should be gaining weight so he told us nurse and then top of sessions with 1 oz of formula. He will take anywhere 2 oz to 4.5 oz of breastmilk or formula sometimes. I have been nursing but doesn't seem to satisfy him and he will nurse hours, so I pump maybe get a 1-2 oz on each side and doing one feeding of formula. I'm trying build up my milk. 
To me he doesn't look like he is gaining weight even though he is a lean body type. We have an appt on Monday to check weight. Another appt with lactation specialist on Tuesday to weigh before and after nursing. 
I'm afraid Monday appt the Dr will make me feel like a horrible mother and admit my son into the NICU. Any other moms have been thru something similar?