I think one of the worst feelings is that of being stuck in quicksand.
Not literally but in the sense that you're just reacting to things. It gets exhausting and then you're suddenly lagging behind a little bit.
Given you're already starting each day at a deficit, it feels like you're now in a race to get back to normal. That is, being on top of everything, planning ahead and so on.
I guess it's just noticing the gap between where you're at, and where you could be but that in itself can be stressful. More so than any actual task or project on your plate even.
There could be a word for it but I usually just refer to it as quicksand because it feels like the more you stuggle, the more tired you get and the deeper you sink.
Whether it's work or side projects, it becomes tempting to spend even more of your personal time ironing those out so you can get back to square one but it never really seems to happen.
Usually that's a pretty good sign that you're doing too much stuff that you really don't need to.
In the case of side projects, or all the things you "wish" you were doing but never seem to find the time, it might be a sign that you've got stuff on your backlog that you don't really care about.
If I were to look in my projects file right now, at least half of them are things that I haven't started and looking back, I don't really care to do them but feel like I should.
In the case of work, I think I just forget that you can say no to things that don't have any benefit to yourself.
Not in a selfish sense but it can be unbalanced if you're just saying yes to a lot of things because you can, or because you have some knowledge to share, rather than because you want to participate.
Anyway, you should go have a hard look at your projects and see which ones you don't really want to do.
You're better off with a short list of things you actually enjoy than a long list of crap that'll just weigh on your mind.