Feeling Discouraged

What do you do when you just feel tired and discouraged? I am prediabetic and have been watching my food intake closely. I test my blood 3 or 4 times a day to what, if anything, makes it go up . I have been doing pretty well by keeping the numbers under or around 100 all day long. But if I have 1/2 sweet potato for dinner, the number does not come down very much and is still in the 90’s when I wake up. Also, I am not sleeping well and wake up multiple times feeling very hungry and expect the number to be low fasting. This discouragement bleeds over into my business. I don’t feel like calling more people and trying to attract/find more clients. I have been at this 3 years. I have a PT job that is flexible and I enjoy. When do you throw in the towel? My alternative MD has tested me for foods and she says even more foods are off limits right now, like night shades (I enjoy my salads and sweet potatoes). Any suggestions for what to do with discouragement? Maybe it’s the sugar and flour withdrawal. Thank you!