What about Biostatistics or bioinformatics? Great job prospects and matches the academic interests of second interested in math and see aspects of biology.
Find the books “admissions possible” as well as " the college solution" at your local library. You’ll have info on the process.
UC’s have one process.
“Meet full need” colleges have another one (including Questbridge).
Go to the website Essay hell and read the advice for can applicants working on the UC essays.