You're definitely doing really well! With continued effort you could probably get all 9s, though I am speaking as a Y13 student who didn't do proper GCSEs.
Don't stress too much though, 'There are no GCSE (or equivalent) requirements for entry to Cambridge. GCSE results are looked at as a performance indicator, but within the context of the performance of the school/college where they were achieved.' Even your current grades are great. If you do decide to apply to Cambridge later on, I believe the interview is the more important factor in getting an offer, (I don't know this for sure).