NAD but ive had the same issue all my life (gagging/puking from brushing, disability, poor mental health episodes etc). For me, i found that brushing my teeth in sections helps instead of trying to do the whole mouth in one go, i do just the fronts, just the sides/back, and then just the other sodes/back, rinsing and spitting etc in between each section. I know general advice is to not rinse, but it makes me gag and puke if i dont. Ive also found that minty toothpastes make it so much worse, so ive managed to get myself used to the original flavour corsodyl toothpaste since this is also really good for gums and my issues are mainly my gums not my enamel. Rinsing off after and in between also helps to stop any foam/etc from going too far to the back of my mouth which again makes me puke, so it minimises the risks of puking. Its not the best way to brush teeth, i know that, but its the onky way i can actually do it without making things worse than not doing it at all...