babies need to be fed when they need to
sounds like you are doing a fab job!

in your other thread you mentioned you ds being a quick feeder.
you can try things like burping him gently, tickeling feet, changing nappy - all to wake him up if he is falling asleep during his quick feed. then it may encourage him to feed more after all that.
but i wouldnt worry if those ideas dont work, his tummy is still so tiny. he will soon get older and start to slowly feed a little less on his own