Changing my mind is something I've always struggled with. One psychiatrist I saw suggested there might be "a bipolar element" to what has gone on with me. And, in retrospect, I can see where my "sudden flashes of inspiration" could perhaps be explained as being episodes of hypomania. I'd get all excited about some new project or activity, I'd be awake three-quarters of the night thinking about it, & then the next day I'd run out & spend a bunch of money to get started. Then a few days later I wouldn't want to do that anymore. I'd want to do something else. So whatever I lost sleep over, & spent money on, just ended up gathering dust in a closet. I would also have a tendency to fall into depression if I started something & then couldn't get out of it... such as a project that involved other people.

I think you're absolutely correct. You don't need to justify what you do, or don't do, to anyone. But, of course, the problem with constantly changing your mind is that it makes it difficult to accomplish anything or become competent at anything. I always wanted to really excel at something. But, logically, that was never going to happen (& it never did) because I kept jumping from one thing to another. And, from that perspective, perhaps there is a sense in which the reason you feel the need to apologize for changing your mind & choices is because "in the back of your mind", so to speak, you feel as though you're letting yourself down?

You asked how you choose & stick with something. Unfortunately, I don't know as I have an answer for that. I suppose that would be a good subject to discuss in therapy. I'm not a psychologist or therapist. So I'm not conversant with how the mind works in these kinds of situations. But perhaps there is something going on with you, in terms of your mental health diagnoses, that would explain why you keep changing your mind. And, if you can discover what that is, perhaps that will lead you to the answer as far as choosing & sticking with something (sort-of like what I wrote about the possible bipolar link to my own struggles in this regard.)

The other possibility I suppose might be that you're simply afraid to succeed. And continually changing your mind prevents you from ever having to face that possibility. I don't know. These are just my idle thoughts with regard to what you wrote. Maybe, in the end, you just have to pick one of the things you enjoy most & make yourself stick with it no matter what... if you can do that. Unfortunately I never could. So I can't really tell you how to accomplish that. But I wish you all the best with your efforts in this regard. The fact that you have insight into what you are doing would seem to me to be a very good sign (even if you haven't, as yet, figured out what to do about it.)