Oh dear so sorry it didnt work out for you, might be worth a try for 3 nightds if you feel up to it. I dont think its alot of milk for a 20 week old, my LO has never been a big drinker.
SHe is now 6 1/2 months old and has breakfast, lunch, tea and three bottles of about 7oz each and we are forever trying to get her to take more.
in the past four nights she had been waking at 5.00am something she never does and we discovered it was due to hunger, we ended up giving her ready break just before she went to sleep and she managed to sleep through until 6.45am
I do wonder whether it could be a hunger thing, have you thought about solids at all?