How do I know when my mother is going to pass?

Christina your mother is very close to death. the breathing you describe is called Cheyne Stokes and her absent brathing may last up to a minute which is very scary.
Don't worry about the bathroom, it is just a sign her bodily functions are shutting down. Don't try and feed her unless she is alert and asking. just take a swab and moisten her mouth for comfort.
When you are in such distress call the hospice o call nurse and she will come out and give you support.
You may see parts of her body turn blue usually start ing with the hand and feet, this is all part of the process. it is caused by the heart slowing down and saving it's effort to get blood to the brain.
I don't know what is wrong with Mom but if she stars to have white frothy discharge from her nose and mouth try turning her to one side. keep a towel under her mouth to catch the liquid. if you know how to check a pulse or take blood pressure you will find her pulse racing and blood pressure dropping. Don't worry if you can't do these thing they are for information only at this time.
if you are believer now would be a good time to call in a minister of your faith.
Is there anyone who can come and keep you company tonight? This is a very lonely time to be beside yourself. Even if they are asleep in the chair it is a comfort to know you are not alone.
Hospice does offer grief councilling for 13 months after a loved one dies both one on one and in groups so take advantage of this if you can. Blessings as you face one of the hardest nights of your life. There is usually someone awake most nights on the forum if you want to talk. people understand what you are going through

I think you should be able to call your Hospice nurse 24/7. Someone else here might correct me... But I would call.

Christina, don't be afraid to talk to your mom, even tho she prob won't be able to respond in any way. Use this time to tell her you love her and give her comfort, maybe even hold her hand? That's what I did with Dad when he passed, as I read somewhere that they can probably still hear.

our hospice you can call 24/7. On weekends there may be an answering service but a nurse will call back within ten minutes. On another note, while people here mean well and have had lots of experience, it seems to be that people who do not have medical training (or even if they do) should not be making definitive comments on when someone will die. Especially as they have not examined the patient and can only go on what the LO is reporting.  They can preface comments as "in my case" or "our experience" was such and such, but people should not make definitive comments on this. I have read some very wise comments on here from people who said even a trained professional said their LO had days to live, only to find out they had months or more.

I myself have asked the forum what they think about this in reference to my own dad. People generally answer that in the case of their loved one, here is what happened. That is fine. But to make definitive comments I think is a bit dangerous.

Thank you all so much! I am going to call the nurse due to this being my first time with this. At the age of 32 I feel lost at times when watching her. I get so scared!