My baby is a snacker

My daughter is 3 days old and is pretty good with nursing. In the hospital she nursed every 1.5-2 hours and brought my milk in rather quickly. My milk came in yesterday before the 48 hour mark. The problem is she will only nurse on one side and for a maximum of 5-10 mins. Is she getting enough? Sometimes she will wake up hungry and want to nurse not even 20 mins later. I know they go through a cluster feeding stage but I’ve pumped and given her a bottle of breast milk and she will then sleep 3 hours. So it seems like she nurses for a short session and then wants more. I’m already getting engorged and I pump about 2 oz within a 1 1/2-2 hour time frame even after she nurses. She never takes both sides and my breasts are literally really heavy so I’ve been pumping. Idk what to do anymore but I feel like even with pumping and nursing every 2 hours or more frequently that my breasts are always full.