Hi Ginnie,
I'm glad you have a proper diagnosis, and some meds, but so sorry you went through all the frustration
dd was on Domperidone alongside the Ranitidine from 8 weeks old (when her reflux was diagnosed officially ) and never had any apparent side effects. She took it until around 18 months, when she was walking well, and we stopped all meds.
We used to put her in a bouncy chair, at 45 degrees, and attach toys with sucker thingies to nearby tables....or hang them off other furniture...but once she had the reflux meds, she as ok on her playmat/gym as far as I remember. Perhaps her reflux was milder than your ds's, or maybe it was better controlled - either way, as long as she was awake we could lie her on her back to play (I don't remember doing that till she was at least 8 or 9 weeks old, though, if not older).
I'm sorry I can't help much with feeding...we didnt' have a problem with BFing initially, though once she'd had a week in hospital being tube fed (bronchiolitis at 4 weeks) she lost the knack a bit. After that, I expressed and gave her BM in a NUK bottle, as well as BFing, and that seemed to go down well too.
What I do remember, very vividly, is that wind and general abdo discomfort was much worse from 6 to 12 weeks, then got better. I think thats partly just normal for any baby - and partly because the reflux meds had time to kick in. You may just be in the worst patch now, where a certain degree of survival (with lots of support!) is inevitable - I don't know.
I would think a bigger baby would have bigger tubes, but have no idea - what I do know is that its totally normal to be wanting to clutch at anything that says its going to get better soon, I remember that well. The largyngomalacia in itself, afaik, gets noisier - but not necessarily 'worse' in terms of breathing or reflux. The reflux is problematic in its own right, till its adequately treated.
If you try Domperidone with the Ranitidine (and dd was on max dose of both for her weight - needs adjusting as the baby grows) and its not enough, I would personally go back and ask for Omeprazole instead of Ranitidine - its the next 'step up' in meds, I think.
I'm glad the sleeping positions help - we also put books under the head of the cot, with dd. Maybe, if possible, don't worry too much about the crawling/rolling bit until you've addressed the reflux a bit more - less tummy pain will make it easier to put him down, and then the rolling/moving may help the tummy pain in return, eventually.
Sorry, long and vague answer, jsut really feel for you and want you to know you're not on your own in it all