I am so sorry
it's always tough to lose a friend or family member, no matter how small. One year and 10 months is still a good life and it may have just been her time.
There's no way of knowing fir sure what happened unless you ask the vet to send off her body for testing, but at this point it might just be upsetting for you. Was the bedding the cotton type fluffy variety? If so, it is possible she choked on it or similar. Again, not much point speculating now. Don't feel bad or blame yourself. Take some time to remember and mourn.