Your blood sugar is in a constant state of flux, depending on when you last meal was and what was in it.
The pattern you describe sounds to me like your body is working on the carbs in your food, which is why they get a bit lower, and that is good, your pancreas is still working. But those readings are way too high, you need to do something to bring them down.
Testing is only worthwhile if you make use of the information to modify your diet, at the moment the readings are confusing and you are not sure what to do with them.
I see you are a T2 on diet only. Whatever dietary approach you adopt as a T2, succesful diabetics reduce the amount of starchy carbohydrate they eat, even the people who wouldn't identify as low carbers. You need a diet that gives you the results you want and that you can stick to for the rest of your life. But you need to get those readings down quickly.
Look in the diet and food forums here and try to find something that will work for you because you will have to stick to it for the rest of your life. Ask questions and use the information you get from regular blood tests to bring your readings down.
And I use my lancets more than once
