@xxJustGabixx I'm sure you have talent, you just need to keep practicing is all and learn how to use all the different features that Pixlr provides. Trust me, I have been making covers for a couple of years now and I'm still not at the level I want to be. I think the only problem you face is that you like to do things the way you want to do it, rather than basing it on another's ideas, some people are like that and would rather do things on their own terms. That's probably why you do better at drafts, rather than when your making official covers for people.
Trust me, practice makes perfect! And I'll prove it to you :)...
Here are my older covers from the first year of when I started: http://imgur.com/a/OEIvR#20
And here are my most recent: http://imgur.com/a/PLLZA
Do you see the difference? ;)