I got a Cambridge offer with 3 GCSE A*s and stated plans to retake AS levels.... what they liked was that in my personal statement and my interview, my passion for the subject shone. Remember, they're looking for people they want to work with who share an interest and intense work ethic, and an upwards trajectory of performance in exams is also liked - which you have shown Imo. Best apply and be rejected, rather than wonder what if. I was not thinking of applying at all, for similar reasons as yours, but my teachers encouraged me and I'm so glad I tried.