Hi @mistymirror, and no problem at all.
This is going to sound crazy but all I really know is that my mum was having difficulty eating. It was back in 2008. She had various tests (for instance chest x-ray) but they kept coming back negative, until she had an endoscopy and that is how she was diagnosed. Unfortunately at that point it was very far advanced.
My mum tended to keep things to herself, but when I look back I remember her cooking Sunday lunch for everybody (or sometimes I would cook it) and she wasn't really eating very much at all. Looking back, it may be that she was eating when we were not around to watch (as I noticed she'd started buying a lot of ice cream and crisps, which wasn't like her). At that point she hadn't told us there was anything wrong, but sometimes it's easier to see things with the benefit of hindsight etc. She was pretty skinny, but she'd been very slim for a long time naturally, I think, so that didn't seem odd.
As for the motility disorder, and how that might present, I've just been diagnosed with one myself (duh...). I can tell you that I've had regurgitation of food (rushing back up into my mouth and needing to be spat out, in what feels like gallons of saliva/mucous) into the toilet. Ugh. That progressed to some episodes of explosive vomiting and has now progressed to agonising pain on eating, a few weeks ago, so that I'm currently on a soft-food diet and having some tests (starting today, as it happens). When I read what you wrote about your mum bringing stuff up when eating it rang a bit of a bell, and so I've mentioned this as just a possibility as I now know it's very rare and so often missed. Although it can be an annoying condition it would be a better outcome for your mum than the cancer you're worrying about, so again - if the biopsies don't answer the questions do look into it, just in case.
I'm thinking of you. If you have any other questions then please don't hesitate to just ask me ❤️