I would say, keep doing what is working for YOU. Yeah, diet soda is full of artificial stuff, and any artificial sweetener will be criticized, but if it is keeping you on track, it's your choice

that being said, I love diet soda

had my first Diet Coke when it appeared over 30 years ago
The pickles, hmm yes the sodium content in them is pretty substantial, but you probably account for that with your other food choices. Maybe think of having a bottle of water for each pickle to compensate.