I have seen many STEM major applicants to UC Berkeley with almost perfect GPAs from very competitive high schools and test scores get denied, especially if the applicant falls within a group of students who are well represented at UC Berkeley. You need good ECs or volunteer hours or something. All I know is that GPA and SAT/ACT test scores for STEM majors are much higher than non-STEM majors at UC Berkeley. I think you will get into UC San Diego though. Not trying to scare you, but this is the reality.
Now that UCs have changed to prompt questions rather than open-ended personal essays, I don’t know what the effect will be.