To respond to a couple of your points:
1. The FDA analysis drew a cutoff at April 2011 for analyzing observations. This was really before the sexual side effects issue had received any significant media coverage so many people didn't know about the effects yet. Since this cut-off (I have done my own analysis) the reporting rates have been growing exponentially. In the year following the cutoff, about 50 additional reports had been submitted that should have been included in the FDA analysis. The FDA also had to eliminate a lot of reports due to incomplete information since the database is very poorly maintained. A lot of reports had missing treatment dates, concomitant medications, adverse event dates etc and many of these were thrown out because the FDA analysis was almost as conservative as it could be.
2. The FDA website is actually quite a nuisance. Many people have tried to submit their reports and were deterred due to the complicated nature of the site and the ambiguous information that is requested. Chrisis is a member here who tried to submit a report but he gave up after a couple of days.