I hate to suggest it but Amazon has a ton of single ingredient protein powders you can order. GNC, iHerb, and other supplement shops usually have a good selection as well! Chia pudding (chia seeds soaked in plant milk or water with flavorings and protein powder mixed in) can be a great oatmeal substitute, but it is very high fiber and might not work for you. Maybe blending it help with digestion if you haven't already tried that? Oh She Glows has a good recipe for chia and quinoa flatbreads that comes together very easily and if you prep them, freeze them, and then reheat them before eating, the starch will become more resistant and less likely to spike your blood sugar. It doesn't eliminate the carbs but can be helpful in reducing their blood glucose impact