For me, the problem with the Fermi paradox is that we only have one poorly understood and incompletely documented example of a planet with intelligent life from which to draw conclusions. Beyond that:

* How many habitable planets are out there? We're just now starting to get data on this, there might be a lot

* Of those, how many develop life?

* Of those that develop life, how many develop intelligent life?

* Of those that develop intelligent life, how many advance to the point where they're capable of interstellar travel? How many are interested in interstellar travel?

* What if FTL travel is simply not possible? STL interstellar travel could basically be a one-way trip. Maybe most (or all) alien civilizations are unwilling to explore beyond a few light years.

* What is the lifetime of a space faring civilization? maybe all the alien civilizations just died out before they explored very far.