Breastfeeding.. help!

My daughter has done AMAZING at nursing. She’s almost 3 days old. My milk supply has came in (YAYYY!)... but it seems that it’s too much for her? Her feeding were lasting 15-40 mins. Now she gets on the boob and will cough, so I pull her away and try to sit her more upright and use gravity to my benefit. Or if she doesn’t cough, they seem to only last about 10-15 mins and then she wants more within the hour. Is this normal? Anything I can do?