My progression was pretty similiar to yours with the only major difference being that I started out as a conservative (although I really can't even say that since I passively assented with the political views of my parents until I was about 16). Around that time I became interested in atheism and I went off on a big anti-religious phase for about 2 years. Eventually I settled down and remained an atheist, but became much less vocal about it (just is not as important to me as politics).
After that point, I began to look around for a philosophy of ethics (since atheism by itself is not a complete theory of ethics, just merely a single metaphysical idea). I was turned away from altruistic theories because of their inherent irrationality and because they were the same theories supported by religion ... which I had just gotten out of. Around that time I found Ayn Rand and things were never the same after that. I began calling myself an Objectivist after reading several of her books and I was content at that point in being a Objectivist ... which is basically a libertarian variety despite what Rand said.
Thanks to the Internet, I was eventually exposed to market anarchism and my initial reaction was somewhat mixed. I was open to the ideas presented, but I was hung up (as most people are) on trivial questions like "who would makes the roads?" and ect. After about a year or so of being exposed to voluntarism in book and Internet form I became comfortable calling myself an anarcho-capitalist which is where I remain to this day.
I don't see my position changing in school (currently in graduate school) since the majority of students/people I meet are either apolitical or woefully underprepared for a deep discussion of politics. It would take some doing at this point to convince me that the state is not an evil/coercive blight on mankind so I will probably remain anarcho-capitalist for the forseeable future.
BTW it is good to see that there are other anarcho-capitalists on here ... we are not exactly popular, but I think that is changing : )
