Okay, first off, it's great you know what you love and what you want to do, I know from experience that the sooner you know the better! I highly suggest you take a bit of time to explore other careers/subjects etc, just to discover any other interests you may have (you don't have to pick your a level subjects based on what you may discover - just so you have a hobby of some kind or interest that isn't related to school to unwind).
You clearly have the potential to do well due to your improved grades, so don't doubt your skills. So long as 1) you want/are passionate to do medicine 2) keep working towards getting the grades you want to study medicine further, I think you should do well.
A few tips you can use if you want:
- like I said, have a hobby/interest to unwind from school work
- keep your bedroom and workspace (if it's not your bedroom) tidy (personally I find unorganised spaces make me uneasy so yeah)
- stay connected with friends - they will definitely make school more enjoyable
- I think you've got this covered, but make sure you know what you want and will work for 100%. Biggest mistake I made was listening to people saying 'you don't need to think about xyz now, you've got time', doing that screwed me over as I was too slow to prepare and have chosen a subject I no longer like (I'm in year 12)
- kind of like the previous point, but know what you're willing to sacrifice. You say you don't like chemistry, but if medicine is 100% what you want to do, you need to ask yourself are you willing to invest the time in a challenging subject for you to do what you love in the future?
I really hope this helps, at least a little