I think, Oliver, that perhaps your weakest link at present is your own attitudes about your playing.

I also think that multitasking *is* switching your attention to the various points of playing as you become aware of things you could be doing better while playing. Much like how all the parts of any activity, like driving a car for example, requires being aware of one thing at one moment and another thing the next moment. That's how it works, isn't it?

You can do a gig at the Strawberry Socials and not have to apologize.

I'd say it sounds like you're doing good enough that most listeners would say you are good. You just don't feel good enough yet to be comfortable with that idea.

As I am sure you are aware, Ken, there is still quite a bit of debate about what might be considered multitasking in humans, and if we even actually do it. I tend to agree with the school of thought that the brain prioritizes and switches very quickly, rather than actually doing what amounts to having two separate thoughts going at the same time.
But who knows? I'm no neuroscientist, and I changed my college major from psych to music.

To address the other part of your question, Oliver.. The hardest part of playing violin for me is that I still get caught up in the mechanical process of the physical motions and think in notes and timing rather than focussing on the flow of the music. Sometimes I do ok with that, other times, not so well. But it gets better with practice. Slowly, sometimes. LOL