I agree, don't take the MCAT until you're ready.
It is MUCH easier for the vast majority of us to learn physics (or any subject matter) through a class.
My MCAT studying literally went like this:
Summer 06/last semester of undergrad: Took gen chem (averaged a b)
Fall 06-Spring 07: Did post pac. Took bio/ochem/calc-based physics, got my act together, got all A's/occasional A-'s (3.9 overall)
May 07: Reviewed material for three weeks
June 07: Took MCAT while sick. Stupidly didn't void results at the end (it was an option then--not sure about now) because I felt "I worked for this!" I felt really down after going home and my mom (!) felt so bad for me she paid for me to take the next MCAT sitting in 2 weeks. I figured I may as well study a bit more, so I did moderate-intensity studying those two weeks (mostly taking more practice tests)
Mid June 07: Retook MCAT
July/Aug (I don't remember): Got results of 1st MCAT. I ended up getting my best practice test score, which beat my optimistic target score by one (this is when it was out of 45). So of course I felt down because how could I have possibly done better than my best practice test.
Two weeks later: My second test came back 4 points higher. That was a nice feeling! I still maintain luck must have been a large component.
The reason I think I did so well was I studied for the MCAT for a year by studying really hard for the class. The best way to do well on the MCAT is to do well in your pre-reqs. Since I studied so hard/learned the material so well (and all at the same time--for 3/4 of the pre-reqs), I only had to do a deep review of gen chem and mostly just a cursory review of ochem/bio/physics.
On the flip side--I tried to teach myself Spanish the way you're trying to teach yourself physics. I took 3 years in high school. My school required you to pass a 3rd quarter language class (if you know the language well enough you can skip to the third quarter course and pass that class alone, which is what I asked to do--I was stupid and deferred so long on the requirement that to do anything else would mean pushing back graduation). A teacher agreed to let me self-study and sit in on just the exams so I could get credit for the course. I studied really hard for the first test, and after I took the first test I showed up to talk to my teacher about the results.
I still vividly remember meeting with her, some 20 years ago. Her words were "You failed. You failed abysmally," which are almost a core memory of mine now. I earned a whopping 13%. 13%! Do the math--what kind of grade can one realistically expect when you have 8 exams and one is a 13%? Seriously, what are the odds of getting a decent grade from there? She suggested I drop the course. I didn't want to give up, so I figured out a way to attend class, and I studied my butt off/participated in the class like crazy and I managed a solid B. I averaged about a 95% on my remaining tests--this is four years after having taken my last high school Spanish class (of which I got B's and C's in, so I remembered just the most elementary stuff...), and getting a 13% when trying on my first test. I went from being incredibly and embarrisngly humbled to experiencing one of the proudest moments of my life.
Take my word for it. Do it the right way. Don't be stupid like I was. Seriously. You would have known by now if you are one of the rare savants that can teach yourself a difficult subject with nothing but a book and willpower.
