I would leave things as they are until that appointment really. Your routine is just perfect during the day, the A time and 3hrly EASY is the best thing for your LOs age (usually).
I really think this is a case of needing better medication to control the reflux.
My DS was similar - what I found happened next was I did extend the feeds (and actually went to demand feeding for a while as he was feeding for such a short time and fussing so much) and it made no difference really. He would tend to eat overnight and at the end of the day - but the day feeds were a total mess.
You could *try* demand feeding and see what your LO wants to naturally do (and find out if that is better than what you are trying to do). And if that is 4hrly feeds then fine
. But I would be cautious in view of the poor weight gain - and I think the symptoms of small feeds and bad nights needs consideration of reflux and a chat with your doctor before doing anything else.
I did BF at this age but I do feel a bit out of touch with that side of things ATM - so will ask one of my BFing pals to come and see what they think as well.
((hugs))