Unfortunately, your GPA is not very high. Because of that, I suspect that entering McGill would be extremely difficult, as there is a limited number of spaces for American students. You would likely have to meet a cut-off GPA in order to be considered for an interview. You might want to inquire to them about just how many spaces are available, although I'm not sure they will release that information.
At this point, in Canada anyway, I don't believe that being a female will be an advantage OR a disadvantage. I'm also not sure whether your major will be seen as an advantage or a disadvantage, although if you could pull up your GPA this year, it would look extremely impressive, as you will be succeeding in a tough major. My question to you, since you are not graduating until next year (at which time I presume you will be applying to medical schools), is why not write the MCAT in the summer of 2000? This way, you can concentrate on trying to bring up your GPA (in a very difficult major!) for this year. Medical schools are often willing to forgive a low GPA in the initial years of university as long as the student demonstrates a trend of increasing marks later.
Therefore, I would make increasing my GPA and my MCAT scores the top priority, as without those two components, it will be difficult to garner many interviews. I'm guessing that your workload in the summer will be easier than the spring, therefore I suggest you spread yourself out further. Tackle the GPA this spring, and nail the MCAT this summer.