The odds of being allowed to transfer are pretty low. I think "snowball in hell" is the appropriate metaphor.
You need, unless I am grossly mistaken, a really, really good reason, and you have to convince the school to which you want to transfer to "accept" you. What is their incentive for adding you to their roster?
I think you should just "tough it out" and learn to love your medical school. If you are not happy there, what makes you think you will be happy at another medical school?
I will start a flame war, but there are no "bad" American or Canadian medical schools. All of them will adequetly prepare you for whatever residency program you care to name.
I can sympathize with you about missing family. But again, just "tough it out" and after a few more months you will miss them less and less. It's inevitable.
Unfortunately, Panda Bear is right... once matriculated it is very difficult to transfer, and then it is usually only possible after the SECOND year, which provides for discrepancies between schools curricula in the first two years. Also, you need a VERY GOOD reason to transfer, especially if you want to get into a California school. "I'm not happy at my current school," is generally not enough... they are looking for more solid reasons, such as a spouse that's back home, etc. Your best bet is to give your school a chance. More than likely it will just take you a little time to get readjusted to a new environment. If not, then you must question your priorities, and how important medical school/medicine is to you vs. being close to your family. One thing I would NOT recommend is to drop out of your current school and then reapply... once someone has matriculated and then drops out (whether it be that they left on their own accord, even if their grades were good, or were asked to leave), they have virtually NO chance of being accepted somewhere else... all other medical schools will think of you as a gamble and likely will choose other applicants over you in this scenario.
Most of the medical schools have something about transfer students in their online FAQ so I'd check there first - but the ones I've seen all start out with things like you need to have a spouse who is faculty or student or resident at that institution -- and then they go on with the other criteria.