This sounds sweet! You don't suck at making full tracks just give it a try, you can add anything you want to it, it's your song! I used to have the same problem, always ending up with making short tracks. Most of the time I felt like I couldn't add anything that would make the song better, but if you experiment and fool around a bit I'm sure you'll get something more going. Maybe add some sort of intro before this part kicks in and have a different chord progression at the end.
You've got an awesome start so far!