Looks like you are doing good for a beginner. The Glock trigger is more like a staplegun than a normal trigger. You are actually completing the cocking of the pistol as you squeeze the trigger and it takes some getting used to. Getting a proper grip in it is very important. For $9.00 you can get a ZEV spring kit for it and improve it immensely. Here's Todd Jarrett showing how to properly grip a pistol. Then one of me at a USPSA shoot with your Glock.
Todd Jarrett on pistol shooting. - YouTube
Stage 3 USPSA 11 26 2011 - YouTube