The crazy part is that about a half hour later he wants to eat again! But by that time it's right before his sleep time so then he just goes to sleep.
Sorry, I thought by this you meant he wanted to eat half an hour after you feed him, no?
A typical EASY for a 3mo would be something like
E 7.00
A 1.5hrs
S 8.30-10.00
E 10.00
A 1.5hrs
S 11.30-13.00
E 13.00
A 1.5hrs
S 14.30-16.00
E 16.00
A 1hr20
S 17.20 for 30-40 mins
E 18.30 (or this might be split either side of a the wind down for BT/bath and be 18.00 and 18.45 for example.
S 19.00
DF 22.00
1-2 NFs at 2 and/or 5am for example
But no baby will do that exactly and many BF babies will need top up BFs before the next nap or will do shorter naps and want to eat early sometimes.
If you were to add in top ups you'd be doing something more like
E 7.00
E 7.30/45
A
S 8.30 etc.
Babies with reflux often want to eat little and often as it soothes the pain from the acid. To feed but big feeds can aggravate the acid problem.
If you think he is intolerant to dairy then only cutting it out fully will resolve that