Okay, I'm going to admit a secret about my writing life. One that almost ended my budding career before it even got underway.
I have trouble ending a story. There; it's out.
For years, although I wanted to write and tried to write, I could not finish any project I started. I had piles of partial manuscripts sitting in folders in my study. And I'm not talking about writing thirty pages and then stopping. I had several manuscripts that were three hundred pages long when I walked away from them. It KILLED me to see these manuscripts just sitting there gathering dust.
Then, a couple of years ago, I took the first step toward overcoming my problem. I told someone about it. The friend I confided in asked a logical question. "Why do you stop?" I was forced to admit that I didn't know.
She asked, "Is it because you don't know how the story ends?" I shook my head. "No, I always know what happens next."
"Then, what's the problem?" Once again, I insisted that I had no idea what the problem was.
This conversation prompted me to do what I should have done in the first place. I began the necessary self-examination to figure out what was wrong. It took several months before I realized that, in the process of writing a novel, I fall in love with my characters. I don't want to write "the end" on their story.
Silly, isn't it? I am generally pretty goal-oriented and pragmatic. This emotional reaction surprised me because it came from out of the blue. However, once I identified the problem, I was able to craft a solution.
Now, when I near the middle of any manuscript, I start something new. For a period of time, I work on both the last half of one novel and the first half of another. Initially, I don't want to leave my nearly finished novel to mess with the new one, but--before long--I become anxious to concentrate all my attention on the new one and am, therefore, willing to wrap up the old one.
I know it sounds goofy, but it works.
The point here is that you need to identify the things you are doing to sabotage your own writing career. It's probably not the same problem as mine. In fact, it's almost assuredly something different. What is it? Are you afraid to send your finished manuscript to an agent/editor? Do you fall apart when your work is critiqued? Do you refuse to accept feedback? Are you unwilling to realize that your early work may just be part of the learning curve and not actually saleable?
Once you identify the obstructions, you can begin to overcome them. Good luck.