I don't agree that you are no good at being adult, Mate. You are great at it.
It's just that adults have a lot of stuff to do. It's a full time job, and we are all trying to do it part time, alongside our actual jobs, so no wonder eyes start twitching.
I intended to adult a lot while on maternity leave. First I was going to do all the self indulgent things my parent pals told me would be impossible after KB arrived. Shopping. Massages. Movies. Waxing. Sitting around. The when KB arrived I was going to do other kinds of adulting, like learning more about economics and volunteering somewhere. In the two weeks I had off before KB arrived my list got so big and overwhelming I got the paralysis you talked about and ended up doing bugger all. Now KB is here I don't even know what economics is any more. I haven't waxed since July. A blood test form is
sitting on top of my fridge, next to a Childcare application form, both of which I got the week after we brought KB home. But we're doing ok. And guess who has two thumbs and manages to take a shower every day? Someone else, of course.