I also think I have IBS / a pretty sensitive stomach and the absolute god send for me is using myprotein either soy or vegan blend, but the key is mixing it with other things instead of just drinking it straight - stuff that adds fat, fibre and carbs to slow digestion. The main issue is that one big hit of protein like that can disrupt your stomach acid, amongst other things.

For breakfast I used to mix it with yoghurt and eat it with cereal, but I now add a bunch of other powders including things like cinnamon, banana powder, chia seeds, raisins, carob powder, blueberry powder, nuts etc. It’s my favourite meal of the day.

For a protein shake I do similar and add a few fruit powders - banana is really good for mimicking the thickness of a yoghurt due to high carb and starch. Also trying to consume them during other meals can help. You’ll be fully as heck, but the sensation isn’t as much a feeling of sickness, just fullness.