To answer your most important questions: Yes, you sound sane, and based on all you’ve told us, it’s a good decision to wait to apply.
And you don’t owe it to us-or anyone else at this point-to justify/explain why you want to be a doctor. Just remember, as part of the application process, you will be asked “why”.
And you’ve been given good advice on where/how to fill the non-academic gaps in you still-developing application package. You have time for the volunteering, shadowing, etc. but you’ll have to be flexible and make time for these activities.
But let’s focus on what you can control: academics. It’s pretty tough to get into medical school, so your GPA is a pretty important number, so dedicate yourself to your studies. There will be other important numbers(MCAT, for example) but work on your classes so that you can give your best possible effort to get the best possible outcome.