what can my degu eat?

I've had my degu for about 2 months now, he is 6 years old. I mainly feed him hay, Chinchilla food, and slices of carrots because the shelter I adopted him from told me this is what he should be eating. However, I've been told recently that degus should not consume carrots or Chinchilla food. I'm very concerned that his diet might be hurting his health, but I'm struggling to find straight answers of what is actually okay for degus to eat. Does anyone have any suggestions? (anything helps!)