There is a very good chance they will come down farther as you lose more weight. Three weeks is not a long time and you've already seen a dramatic decrease, so expect the decrease to continue, but at a slower rate.
I wouldn't restrict your total calories too much as this will cause your body to try to conserve energy thinking that you are starving. What works for me is getting total digestible carbs below 50g per day. If you don't eat sugar, grains, starchy veg, or rice, then you will likely be below 50g a day with no need to count. Also, avoid processed factory food (the stuff with lots of unpronounceable ingredients) and processed veg oil.
Exercise is a good idea. Adding a bit of muscle mass and improving your cardio fitness will help a bit.
No need to be ashamed. Many of us were in the same boat, especially given the dietary advice (low fat, lots of carbs) given to type 2 diabetics by the health care system.