Hi! I'm not an expert at all but didn't want to 'read & run'.
My lo has been on 4hr EASY for a couple of weeks - we do 2hrs E&A + 2hrs S. I guess you could do 2.5hrs E&A + 1.5hrs S? I'm sure someone more knowledgeable will be along to have a look at your routine & more of a chat though!
DS is also a reflux baby & held upright for 20m after feeds. We actually do a df at 10.45pm and he goes through until approx 4am. We ALWAYS wake him to feed at 7.30am - as far as I'm aware the morning feed / time you start the day is crucial to the routine (although as stated, I'm not an expert). Yesterday he woke at 4.45am so it was about 5.20 by the time I got back in bed 💤💤. I think I read once the routine is established you can vary the time occasionally by about half an hour, but should try & be pretty strict, especially with the first one of the day.