Diaper rash already?

God I feel horrible. My babygirl is 11 days old and I think she has a diaper rash. She is breastfed and she poops so much and I think it’s starting to take a toll on her. Her poop is still yellow and seedy which I think is normal but sometimes she has 3 poopy diapers in 30 minutes. Idk what I’m doing wrong. What do I do?