Hmm, not sure why you are mixing those 2 foods, I wonder if that could bring up the protein values.
Getting her to drink a bit more water can help... or putting naturvet - cranberry relief, I have used this for Jazzie, on and off since she first started with crystals in her urine March 2008. With a change in diet, and this cranberry relief, we have not had issues with crystals.
Good for you for giving her veggies and fish. Look into the home cooked recipes on YT, it may be the way to go for you and your furbaby.
The honest kitchen sends samples, they have a formula which has veggies, you just add the meat, it is freeze dried, you mix that part with water and then mix in your choice of meat. Pretty nice.
Good luck.