bubs feeding quick

Jessica
So I'm a little worried about how fast bubs is feeding, we are on our 6th day of breastfeeding and my milk is definitely in( I have so much milk) 
Bubs is only going for five minutes on each boob each feed, most the time he goes  straight to sleep after but if I let him go over ten minutes in total I find he vomits. 
Should I be worried or is this normal ? 
I have never breastfeed before so I have no idea what is normal and what's not.