Mark, I've been thinking about your thread for a while, and have found myself a little stuck for words.
I think I have an inkling of how you feel, though wouldn't say it's the same. I have been recording my mother's house and garden, and more recently the surrounding landscape, since it really hit me that one day not so far off I will no longer have any link to this area (which I have known since my middle-childhood).
At first I started taking photos in a kind of panic, literally I could feel my heart beating faster as I tried to get the shots I wanted - while they were there; I could only do this on visits, as I live a three-hour car journey away. In the end I found I have had more time than I originally thought I would, (though it is the unpredictable nature of the amount of time left that can be stressful).
I found it much easier on myself when I learnt to slow down a bit - that a photograph is only a photograph - and if I managed just one that I was truly happy with it would hold all the other 'potential' photos, and stories, and all the memories, within it.