Your question is very interesting, actually. For me, I must say: no, my actual job is not my desired job, but it opens doors for me to do some activities I love doing. It's more like a mean to reach specific ends.
In fact, the idea of self realization through a successful career or a desired job is nothing more than a social construction of our contemporary society. If you look back to the Greeks, for example, their idea of self realization was to be able to spend whole days involved in non paid, intellectual activities. That's why they are recognized for so many breakthroughs in political, sociological, philosophical, moral sciences. And that's also why they had slaves to do the hard work. Anyway, what I want to show is that this idea of perfect job changes over time and in different places.
My point is that we don't need to narrow our search for happiness: if such a thing exists, it's not based on finding the perfect job.