You are doing a fantastic job so a huge congratulations for that!! Your DS sounds exactly the same as mine. He is stilling feeding every 2 -3 hours but last night he fed every 1 1/2 hours - it nearly killed me but he must have needed it. It is stinking hot here at the moment (up to 43 and still low 30's over night) so he must be needing it for extra fluids too. So it could be that he just feeds that often, needs some extra fluids in this heat or having a growth spurt.
Keep up the great work!!