I having a trouble with creating my ideas

Whenever I want to create something I usually imagine it in my head first. Or put together similar photos to make a rough version. But most of the time, even though they seemed, felt superb at first, I abandon them.

Although, after a while, when I am in the midst of creating process of some other thing the stuff that I didn’t want to create starts pupping up in my head.

I don’t like that feeling. I think the reason why I am abandoning the ideas is bcs I am not skilled enough yet. I having been working as Graphic Designer for almost 2 years I still have zillions of things to learn(I haven’t even fully figured out Adobe Illustrator).

My question is, when this goes away? When I finally will be able create whatever I want, however I want? How many years I have to practice so I can stop feeling guilt of not being competent enough?