Do you test before eating in addition to 90 minutes after?
If you do that and look at the difference between before and after, and keep this below 2mmol/l, preferably less, your numbers will start to drop. More than 2mmol/l and there are too many carbs in that meal, which can be reduced in portion size or eliminated. Keeping a detailed food diary including portion sizes is an excellent plan because if you record your levels alongside the food it will soon become clear what your danger foods are, and also what your safe ones are.