moose- sorry for ds1- this is presumably why he has been vomiting so much recently? He seems so young to have migraine hope they are controllable.
With you on the buggy- you have to use it all the time- it needs to be one you're happy with!
hkz/heron - re reflux- you may find it v useful to raise the head of the crib/cot/ moses basket- whatever you're using- just pop some thick, sturdy books under there- an angle will improve things for little one. Go for as steep an angle as you can. you can get mattress wedges too, but can be £££
When dd was in the cotbed- I used a sheet tied to bars and threaded between her legs so that we could have a steeper angle but she didnt end up in a crumpled heap at the bottom IYSWIM.
Also- hold them upright for 20 mins after each feed- a killer after night feeds, especially if your baby feeds for a long time, however it does make a difference. I just popped dd upright on my shoulder and read- got through quite a lot of books...
Despite having reflux from birth, dd never lost weight- she was always a good feeder, and using above techniques meant she didn't actually throw up much.
We did give her gaviscon after feeds, but I'm not sure how effective it was, compared with the upright positions.
She always hated tummy time too- so you may want to use it sparingly when they're at that age.