Does your school offer a science research class or club? Maybe one in the area?
Top colleges love to see students conducting research (especially if you plan on going into the medical field). If possible you can try starting a research project on a form of female reproductive cancer or other issue related to your career and maybe even compete at a science fair/competition. This will show your interest in the subject. Maybe try going to a research camp/program at your local college or university.
Not a research class at your school? No problem! Colleges love to see kids starting a club or class about something they are passionate about. It demonstrates great qualities such as dedication, persistence and leadership and passion for a subject which is what colleges look for. Try starting a research club with the help of a science teacher. I’m sure he/she would love to help and there would be pleanty of students interested since as previously stated colleges like to see research.
If you don’t want to start a research club, try joining a science related club at your school. Maybe you have Chem club? Physics club? A general science club? If you do join these clubs try to snag a leadership position or become an officer (President/VP, treasurer, secretary, etc). Colleges like to see leadership positions in clubs. If not, you can always try starting a club like those.
Your volunteer work is great, however this doesn’t really make you a competitive applicant as many students do volunteer work for college. If you decide to stick with volunteering, show that you are passionate about it and not just doing it for college admissions purposes. You can do this by possibly starting an organization that raises funds for your local nursing home or hospital. You could possibly start an organization that helps plan fun events for the people at the nursing home.
Ex. Field Trip to the local park for the nursing home.
Game night
Field trip to see the school play
Etc.
I hope this helps and good luck!