If it were me I would be inclined to try the DF a few more nights, it isn't suited for every LO but at least try it for a week.
Glad to hear the faster teats are working.
Calum is also an angel baby, just looked at my log and he was still waking at 0130 for 2oz ( I was trying to cut it down, to eventually offer water) - he also ranged from 33 - 35oz per day - with solids!.
If he is babbling, cooing or Mantra crying and leave him, if he is crying out of need go to him.
Are you on a 4hr EASy?
I am assuming you are if he is having 4 bottles
Emma, I don't think you are having a problem at all, everything you are going through with your LO is normal (at least it was for Calum and I). The next thing that you will probably need to amend your routine for is your LO dropping th catnap (if you still have it).
Out of interest what was he waking at night before you introduced the DF?