I've been in your shoes, trying to do too much yet still thinking I wasn't doing enough. The lack of activity in this forum section is a sign of the same problem. We all concentrate on the patient and forget the caregiver who's working double-time or triple-time and simply can't keep up.
If you can't give yourself a break without feeling guilty, think of it this way: Dennis's health depends on your staying healthy, and that means getting enough food, rest, exercise, and the physical and mental breaks that every one of us needs.
You can play superwoman for a day or two, managing work, home, hospital, and everything in between, but it's not possible to be a superhero day after day, week after week, month after month. Even post-transplant, recovery can be a slow process and you need to make it all the way through.
We all do tasks that we're used to doing but that aren't really that important if we think about it clearly. Let some tasks go. For now. When there's still too much you want to get done then admit that you could use some help. Ask each friend or relative (maybe coworkers too) if they can provide a little help to you and Dennis. Having a few other people pitch in can really help you get through the day and it also does wonders for your state of mind, because you don't have the entire weight of the world on your shoulders.
Like Dennis, you can expect some days to be better and some days to be worse. You both have to keep going and you both have to lean on others. It's for your own good!
I really hope this helps, Kathy, since I know just how you feel.