^"I have this nagging sense of failure all the time about being so lame about getting any little thing done that I set myself"6
That sounds so harsh, Willow - I recognise it, because I used to be (and still am, to some extent) really harsh to myself too.
With everything else that is going on in your life, do you need to add another 'I should...'? You don't have to be productive 100% of your waking hours - and I think it is important to remember that we need leisure time/wind-down, do nothing time, in order to energise and refuel ourselves for all the other things we have to do.
I do think it is important for you to enjoy your evenings - and if you are not enjoying what you are doing now, then it's great to look around and find something else to do. But please don't do it because you feel that what you are doing now constitutes some sort of 'failure' - because if it enables you go do all the other things you have to do, it is not failure, is it.
I would suggest that handcrafts are a good place to start - I love knitting and crochet, because it is lovely to see something grow, and I enjoy having things I have created myself (and giving someone else something I have made is a true pleasure). I also think that the textures and colours of yarn are so therapeutic - well, I find them to be so.
I'd suggest starting small - I followed a YouTube tutorial that showed me how to do a basic crochet granny square, and from that, I went on to look at more complicated patterns, and gradually increased my skills (not a whole lot, I admit - but enough to make things I enjoy making).
If you wanted to make things with a purpose, Mumsnet has a project called Woolly Hugs (there's a website and a FB page). We make blankets for Yorkhill children's hospital, another children's hospital, for prem babies who pass away, for children with cancer in Africa, and for refugees. You don't have to make a whole blanket - you can make one square, send it off, and it will be added to other squares people send, and made into a blanket by a volunteer hooker. We also make blankets for MNers who lose a child or a spouse (that's how it all started). The website and FB page give more information on the sort of yarn, and size of square etc - and EVERY square is gratefully received and valued equally, so if your first squares are wonky, that's absolutely fine!
If you want to know more, I am happy to tell you (and if I have blethered on for too long, feel free to ignore me).