Im glad to hear about another person interested in physics. Here are some things you will need to know.
1) The most important part of physics is math. Math is the language of science.
2) Biology won't/shouldn't hold you back.
Theoretical physics is using mathematics to unlock the greatest mysteries of the quantum world, as well as the macroscopic world that we live in. If you want to become a theoretical physicist, which mainly includes string theory and quantum physics, it would probably be in your best interest to study up on math (calculus, algebra, trig) and relativity. You would be very surprised how much relativity comes into quantum physics and string theory. String theory is a very complex study of theoretical strings that are inside quarks. Also we study how they act on their own in space-time and their worldsheets and how they interact. It is very complex. it is also a very new field to us physicist. If you don't know, MIT (Massachusetts Institute of Technology) releases their classes after they have been taught for free online. I use it a lot. here are all the courses you should look at for being a physicist. Remember these are real courses that were taught at MIT and were taught to real physicists by physicists.
Einstein equations: http://ocw.mit.edu/courses/physics/8-224-exploring-black-holes-general-relativity-astrophysics-spring-2003/index.htm
Particle Physics: http://ocw.mit.edu/courses/physics/8-811-particle-physics-ii-fall-2005/index.htm
Relativity: http://ocw.mit.edu/courses/physics/8-033-relativity-fall-2006/
Modern Physics: http://ocw.mit.edu/courses/science-technology-and-society/sts-042j-einstein-oppenheimer-feynman-physics-in-the-20th-century-spring-2011/
And at last, use any of these courses to get a gist of what being a physicist in training is like.
http://ocw.mit.edu/courses/physics/
Good luck and its great to have a woman interested in this. I am one of 4. and I am the only boy. I was always given a hard time about my physics interest.
P.S. Im only 13, I've been studying and researching string theory for a couple of years now, and my college courses have really helped me become a physicist. Excuse my young age.