Hope for the best and treasure what u have, the remaining time with her. You are lucky to have her for so long, my dad died when I was 6. I did not remember much about him...wish I had more time to know him better.
My mother also died of cancer 9 years ago. Phase 3 when discovered. She lasted 9 more months. I tried to make her happy for those 9 months tho she was on a wheelchair. We hired a rehab bus to take her to good restaurants and the beach. Towards the end, she could not talk and might not even recognise me.
Be strong and try to do things she like best with her.