My little guy is a fast eater too, does not like to be burped in the middle of the feed. He's 4 months now and he eats 6-7oz in about 10 minutes, maybe faster. I just burp him well afterwards.
I use the Dr Browns bottles. I used the Avent ones when he was little, but he would down 6 oz in less than 5 minutes and scream for an hour afterwards...LOL I think you may be able to find even slower release nipples - I found the playtex ones have a real slow release to the point Jack was getting frustrated...there is no winning.