Well, actually you do have it kind of backwards, but not really in a bad way.
The basic progress for scifi in idealized case is to first come up with the concept. Then come up with the theme, which aspect of your basic concept you want to explore and how. Then think of a story that does that. And develop the setting as normal for the story.
So in theory you kind of did part of it backwards. In practice, you are extremely unlikely to have developed the setting to a degree where it actually is an issue. And even if you have, it is your setting, you can make adjustments as you wish. So don't worry.
Note that as per comment it does not really matter where you start developing the story, in the real world the development a story is always an iterative process and there is no requirement you do "all steps" every iteration. So the actual starting point and the order you do things do not really matter. The idealized case comes from the fact that a science fiction story is as per genre defined by its differences from familiar. Putting concerns related to that first is simply a way to ensure you do not forget and write a otherwise perfectly good story that confuses readers because the differences from the familiar are badly exposed.
In any case, it is absolutely normal to reuse settings for multiple stories, sometimes even by multiple authors. And usually it works just fine because of the sheer improbability of the setting having been so strictly defined it is a real issue. The extreme example of this would be the real world which has been used as a setting by literally countless authors without the fact that the setting was defined before making up the stories really being an issue.
Fundamentally this is because any setting is always much larger than either the part of it visible in the story or the part the reader might have any knowledge of. There should always be enough unknown territory for the needs of any story you wish to tell.
Now just think about the really cool thing about your setting that you'd like to explore or share. Then try to think of circumstances where characters in the setting would explore that aspect. If it really was something cool, there should be a story there.
I probably should mention the one thing you do need to watch for. Sometimes when people have a setting with a concept they like and they have spent lots of effort in developing it, the author gets tempted to show it off to the readers. Since the setting is shown in the context of the story, this naturally results in the story meandering about so that it can show more of the setting.This in turn results in issues with the pacing and internal logic of the story,and in general makes the story weaker and less immersive. This is a real issue with modern scifi and a major reason why I read much less scifi than I used to.
So once you come up with the story make sure you resist the temptation to show off one iota more of your setting than the story actually needs. (Success is optional, just remember to make the effort. It will keep you away from trouble.)