Is baby getting enough

I had been exclusively pumping for the first two weeks of my babies life.. just recently I’m trying to exclusively breastfeed.. my baby will eat for 15 minutes total and then just completely pass out. She becomes like a noodle lol.. is she getting enough to eat within 15 minutes?? I use slow flow nipples for her bottles and I wonder if that’s why it takes her 30+ minutes to drink from a bottle. Anyone know what I should do? Is this a normal feed time? Could she be full?