Willow, has he always slept in your room, or have you tried swith him sleeping in another room?
Just a suggestin becuase this happened with us, but I found DS' night time sleeping improved a lot when I moved him in to his own room (I did this earlier than 6 weeks).

This may or maynot suit you I just wanted to let you know it helped us.

Also I think his sleep patterns are well within the range of normal.