Thanks Louise, I sure have more of a picture now
Firstly I think you have done a wonderful job so far. To be honest sometimes with this disease it's hard to really please a PALS because we can't cure them, we can't do anything to stop progression and what they are experiencing I can't truly imagine. Even though I was there 24/7 with my own husband, I can't imagine what he went through.
I think some PALS become a bit OCD even if they were not before ALS because it can help them feel a little in control of something - it's wonderful that you are there to allow her to direct that OCD - I loved that "I'm her OCD cleaner"!
I think you also hit a nail on the head by recognising that there was an issue with another carer, and yep this is hard because you know that you are separate from this, but she is obviously affected by the experience. Have you talked to her about it and expressed how upset you are that it all went on?
The tiring easily is a huge part of this disease. You didn't say if she is using bipap at all? If she is not and she is tiring easily she may need breathing assistance if she wants that. If she is starting to have breathing issues, the big thing is not so much lack of O2, but it's a build up of CO2 and this can really affect her mood - she may become irritable, intermittently sleepy, cross, headaches and difficulty focusing.
To help her I wonder if you can find anything she is interested in that you can do with her - audio books, documentaries, music - and be willing to know she may fall asleep at any point and be ready to mark the place and take up from there the next time.
Sometimes even simple things like a nice place to go and just sit that is outdoors, or looks over a view, or even a fish tank can be very calming.
There isn't any blanket answer, but there are ways to try and find something that will resonate with her as an individual that you may be able to discover.
I have to say it's wonderful that you are taking an extra interest in looking after the person that she is, not just the personal care and cleaning. We will support you however we can here!