How do you know if your loved one still needs something in order to pass?

The Roller Coaster is so HARD! Since 2009, I have been providing support for my mom has has increased over the years. From shopping for her when she no longer could make the trip, to handling her bills, keeping track of her dog, medical appointments, moving her (with help of siblings) out of her home and into independent living community, then assisted living and now to nursing home. She was dementia and diagnosed with triple negative breast cancer in January and went into the hospital because stomach bleed and UTI. They told us she had 7-12 days to live. That to me was when we boarded the roller coaster ride. We called family from Alaska and Colorado and they flew home to be with her. We watched for her to die...and she didn't. She rallied. In those days she rallied, she was precious and loving - much unlike she has been over the years since her mini-strokes. The time has been wonderful and excruciatingly painful - all at the same time. Three weeks ago, wound care Dr. diagnosed her with Kennedy Ulcer - something we learned only happens at end of life and were told she would have typically less than 72 hours left. She had other declines and was not eating much, losing weight, etc. The priest was called and again family boarded the ride down to prepare for her passing. She is still with us today. I can't say that I regret the extra time, but I am beyond weary from the ups and downs of this. She has made several declines over the last months. She has had her last rights, had most all family talk to her for goodbye to thank her, apologize if needed and was given permission to go. We tried to do what we could to make sure she knew she could rest...that we will be okay. We followed the book provided by hospice, but that does not seem to help. She hasn't been eating much for weeks. She is fully bedridden, eats very little, is having hard time even drinking protein shakes from a straw, has has repository problems, oxygen levels changed, lower bp, temperature has gone up a time or two. Not talking as much, etc.

How do you know when it is really time?