To start, enjoy this first! Too often, writers let future work and goals get in the way of celebrating what are very real accomplishments. Let yourself have a moment to focus on what you have done before turning your attention to what you need to do.
Now, on to your concern. It sounds like you’ve tried to write complete stories in the past. That you’ve persevered and achieved this goal is significant. You couldn’t do it before and this time you did. You’re developing as a writer. Just because you don’t want to sink right back into that story and take it apart doesn’t mean you’re not cut out for writing. It just means you’re not ready to revise this particular story at this particular moment.
Give yourself some time. Perhaps you simply need to let this story simmer. Start another. Immerse yourself in a new set of characters, settings and conflict. Not sure what to write next? Work on journaling or writing exercises. Keep returning to the page over and over until an intriguing new character or conflict surfaces. Eventually, you may find yourself eager to return to the other story.
Some writers even get to a point where they feel flattened by the very practice of writing. If that’s how you feel, step away from the page for a bit. Take some time to focus on other interests and activities. Go out into the world and get in the way of inspiration. Set a date to return to the page. You may find you feel quite different about writing when you do.
That story you completed? You may be inspired to return to it down the line and continue working on it. Or you may be done with it, even if the story still needs work. That’s okay. The process of writing is one of learning. That story may have been a practice story that allowed you to explore technique and witness that you’re capable of writing a story with a beginning, middle and end. It’s not a polished final draft, but you’ve still done important work in your development as a writer. Either way, keep your sights on the next story.
I paraphrase the Greek philosopher Heraclitus: You cannot step into the same river twice. The river flows and changes. People, too, are not static. This strikes me as apt for the writing process. Don’t fall into the habit of taking a specific situation with one story and applying it to your potential success as a writer. The dynamic will change every time you return to the page. See what you find there with this fresh perspective.