The next logical level of Math to take is Pre-Calculus. You will probably have to take some Calculus in college so having some exposure to the material in Pre-Calc will definitely help you.
A Biology major is great if you want to apply to Medical school, Physician Assistant school, Dental school etc… As a stand alone major, not very marketable without some graduate degree. Biology can be rigorous depending upon the curriculum and area of concentration along with your interests and your strength in science based courses.
Biology related jobs: https://www.monster.com/career-advice/article/best-jobs-biology-majors-0317
Microbiology, Public Health, Kinesiology, Speech Pathology, Nursing, Molecular Biology, Biochemistry, Environmental Biology are other majors to consider.
If you are looking at the CSU’s and UC’s, then probably 1-2 semesters of Calculus and 1-2 semesters of Statistics could be required for a Biology major and this probably true for most science related majors.
Most college websites list a 4 year plan for each major so you can do some research to see how Math heavy any of these majors can be.
Here is a link for SDSU’s 4 year major maps. Just select year: 2018 and major: Biology, Microbiology etc…