Ups and downs?

Rue
Hey all! I've really been trying to control this GD with a strict diet, like we've all been instructed to. Today I decided I could try a decaf iced coffee (skim milk and Splenda (which I've read is approved during pregnancy)) with my snack which was a Kind bar. Ate a burrito bowl from Chipotle for dinner, which has proven awesome for my numbers time after time. After taking longer to eat than normal and not being able to go for a walk, which is totally not the norm, my number was 161!!!!!! I haven't been over 120 after a meal in well over a week and I have NEVER come close to anything in the 160's. My stress is getting the best of me and I feel like I'm failing, despite the bout of perfect numbers for 10 days+. 
How do you fight the feelings of defeat? GD has been such a roller coaster for me. One bad number and I can't seem to get it under control for a few days, then I'll be perfect for a while again. Any advice guys??