How long does your newborn breastfeed for?

Hi , I’m FTM here with 12 day old baby and still figuring out breastfeeding. My baby doesn’t latch well. And only latches on right boob😅. Im pumping to keep my milk supply and I’m also supplementing with formula when needed.

How long does your newborn breast feed for in one sitting ? My baby only latches for 10-15 and stops and goes to sleep. I also pump and able to get 100ml in 35mins of pumping or sometimes 70ml. Pleas help and let me know your input. 😊really appreciate it.