I still have muesli which I make up myself sort of. I buy Dorset Foods Simply muesli/ or the nutty one which has no sugar and is the lowest carb one. I pour half a pack into a big tin add the same amount of large organic oat flakes, some rye flakes, barley flakes, wheatgerm, linseeds, pumpkin seeds, sunflower seeds, toasted sesame seeds, goji berries, raw cocoa nibs and mix well. I have 4-5 tablespoons with yogurt in which I mix cinnamon and soya milk(low carb). Ok you have carbs here buy low GI ones and there is a lot of fat (in the seeds), protein (nuts, seeds, yoghurt and milk) which helps to slow down the passage of the carbs through the gut. Try testing after 2 hours and I am sure you will find it fine.
When I first did low carb/low GI I tested all the time to see what I could and could not tolerate. e.g. I can't take rice but I can udon noodles - don't ask me why!! I also don't tolerate Malitol which you find in diabetic friendly sweets/chocolate so I eat 85%+ chocolate if I fancy some.
The best bit of advice I was ever given was to eat my fruit with a meal never on its own (it spikes!).
Good luck