you did amazing, well done! you still have so much time to improve, my grades went up a lot between Y10 and GCSEs.
just use the next few months to work on what you've struggled with most so far in the course, your mocks are a really good indicator of what you understand. i would go through your papers, making note of all the topics you've not done as well in, and i would prioritise those.
also, as frustrating as it is, it's quite good to have teachers who are harsh with marking, as that way your grades are more likely to be higher when they're being marked by actual examiners - because you learn to perfect your answers and automatically work harder than most to get the top marks. this is a technique that's really helped me in my A-levels and i'm hoping that it pays off on thursday!
it is pretty hard to get straight 9s at GCSE, but i do think that you can continue to do really well and this can certainly become a possibility, just keep studying, make sure not to burn yourself out though.