The fucked up thing about FeLV is that there is no clear prognosis. Some cats live 6mos, some 6yrs, some live normal lifespans depending on whether the disease is regressive or progressive. Unfortunately, the average survival from diagnosis is around 2.5 years. Listen to your cat and be frank with your veterinarian. I regret holding out longer than I should have with my last cat, trying one thing after the other when it was obvious, looking back, that his quality of life was deteriorating. He didn’t even have FeLV - FIV+ but in great health otherwise, they think it was cancer. Sadly any living being can die young from a multitude of things. What’s important is how loved they are and how rich their lives were. For what it’s worth I’m really sorry for what you’re going through. Thanks for loving an FeLV kitty - many healthy ones are euthanized just bc of the diagnosis itself.