Agree with @raclut that it’s important to build solid foundational skills in hs, premed or not. Med schools don’t require one to take the most rigorous courses, majors, etc. Academically, med schools req a BS/BA and premed reqs. Besides premed reqs, what you fill your dance card with (aka classes/majors/minors etc) is up to you. Just do well academically, fit in time to prep and do well on MCAT, participate in ECs, have a college life, etc, all the while keeping in mind that there are only 24 hours in a day. Although a semester system (15 weeks) is most common, if you attend a school using a quarter system (10 weeks), the shorter duration can be GPA crushing if not prepared from day one… Sure it’s okay to take more science courses that are not part of your major/minor, just do well. Taking more science courses may be important if you stumbled in some premed science reqs, but are typically not required, nor do they give you a head start on med school, nor will they necessarily tend to awe med schools. Most importantly, enjoy rest of your hs years.