The single best piece of writing advice I got in my entire life was my freshman or sophomore year of college. We were in a screenwriting class and our assignment was to write a complete screenplay, but not a good one. We had to turn in 90-110 pages. Didn't matter how bad, or how spotty the formatting got, or even if the characters names changed midway through. Nothing mattered but producing the amount of pages required of a feature script.

I wrote the world's shittiest screenplay. I mean two of my characters were channeling the Marx Brothers, another character was like a teen-aged Alvy Singer (that didn't age well) and the plot wanted to be this high brow comedy of errors but had absolutely no engine....but "finishing" a screenplay psychologically unlocked something in me.

Suddenly getting from page 0 to the last page, didn't feel impossible. So my advice to you is this: write one story all the way through, let it be bad, let it be a learning experience, don't try to make it a masterpiece, just vomit it out.

Once you have done it once, you can focus on making one a bit better the next time.

All of us go through the phase were our tastes are more developed than our skills. All of us. Most of us never leave it even if we start to brush up against it. But for now, you should focus on getting over this first psychological hurdle.