My little markiza is gone , poor kitty

[Catherine]

It sounds like she must have had a serious heart condition. Even if you took her to the vet there might have been nothing the vet could do. Licking things is not a common symptom of heart trouble. It is certainly  not one I have ever heard of. I wouldn't have gone to the vet either. It is sad that you have lost her and I know you wish you could have her back. You shouldn't be too hard ln yourself. You gave your cat the best of care. Sometimes it is just not possible to prevent something from happening.
Be at peace with yourself. It is normal to feel some guilt when we lose a pet, but it is not actually our fault. You cared for your pet and you gave her the best care you could. Sometimes that is not enough. She died because there was something seriously wrong with her heart. You at least gave her two happy years of life with you. Her life was short, but it was good. She was like a spring flower that bloomed briefly and was gone. You will always remember how beautiful she was and you will cherish every memory you have of her because there are so few.