You got 6s, 7s and 8s for your sciences so that is not bad. On the other hand its rlly good so well done!
To be able to do medicine, colleges or universities would prefer students to take biology and chemistry for A levels as those are the main subjects that would be useful. Hence, seeing that your GCSE grades for yout science is high, without a doubt you can get in. Ofc applying for medicine is hard work and is indeed competitive. I don’t see a problem with your GCSE grades, ofc ur gonna think that you could have done better amd that’s normal, we r humans.
And your A level predicted grades are OUTSTANDING!! so I believe that you will get into medicine.
I hope this helps, all the best ^^