Don't worry. It is done now. Do you mean you are worried that you accidentally plagiarised because you did not reference work that therefore appeared to be your own or that someone will plagiarise your work?
Or you did not use the reference system properly?
I bet it will be fine even if you made an error. It must happen. It can be tough for A level students to learn these skills when they are not even at university.
Also, it looks like AQA won't be moderating them this year from what I can see. Happy to be corrected on this but that seemed to be the result of the consultation. So it may just be your supervisor marking it and they don't appear to have raised it as an issue so maybe you didn't.
I would say - just take it as a learning experience should you go to university. A useful lesson learned - to be as careful as possible to reference other people's ideas and words. Better to learn that lesson now than get in trouble at university.
But whatever you do, don't worry. It won't do your mental health any good. Just decide it will probably be okay and learn from it going forward.