Bottomless pit baby

My son is nearly 6 weeks old, I'm exclusively breastfeeding but my husband likes to give him a bottle occasionally so I can have a break. He eats between 4-5 ounces. Tonight he ate a 5oz bottle then was screaming acting like he was still hungry! He's been nursing for over 18 minutes. Is he getting too much? He hardly ever spits up. Seems a bit much to me.. How much do they usually eat at this age?!