I think you really need to go back to basics with her.

Do you have access to a puppy or kittening crate at all....just to borrow. When she is indoors, place her in the crate with just her bed, food and litter tray. She will not want to urinate on her bed or food so she will hopefully go in the litter tray. I am sure she will moan and cry at being shut away but if it has been going on for so long, you really need to start as though she were a kitten. This should help her relearn where to go and where not to go. It really should only take a couple of days at the most and if she is an outdoor cat anyway, I see no problems with having her confined for a few hours at a time. Once she starts using the litter tray, you can then start letting her out into the kitchen and see if the problem is sorted out or not.

I have done this a couple of times in the past and it has worked brilliantly.

Lou
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