Hey dude,
I personally began to have doubts whilst earnestly trying to learn more about Islam. The doubts increased and led to my eventual apostasy after watching many youtube vids critical of Islam/religion, and reading apostasy testimonials on wikiIslam.
But also in hindsight many of my beliefs in the validity of Islam was undermined indirectly through my persistent interest in psychology, spirituality and holistic healing.
Here are the testimonials I mentioned...
http://wikiislam.net/wiki/People_Who_Left_Islam#All_TestimoniesThe youtube channels I personally recommend - in no particular order - are;
Cembadmins
Theramintrees (check out the video; religion - the bad parent)
Therationalizer (The scientific miracles of the Quran debunked)
Evid3nc3 (incredible presentation of his deconversion for christanity, that helped me greatly to understand my own deconversion process)
Phillhellenes (check out the vids; science saved my soul, and why didn't anybody tell me)
Take your time man.