You could have many ideas... If that's the case you're just like me.
What could be stopping you from writing on those stories you start, is that you don't have much on them. You haven't thoguht about them.(Why not?)
Would this fit your case? Because this is what I notice with mine.
I kinda have images of what I think would be cool for a story to have, but obviously I'm not gonna write it from beggining to end right away.
It takes time. And you shouldn't give up because of that. First of all, you should like what you're writing.
What's wrong with you?
Nothing, in my opinion.
The only thing that I see is a mind capable of having lots of ideas.
That's all you need to expand on the little images in your mind and little scenes that grow out of a dialogue you create.
Have you thought about joining two stories, for example?
Because having stories for each little thing you come up with is kinda too much and you never start accumulating depth.
As you come up with new stuff try to incorporate that new thing into a story you've already thought about a lot.
If even so it doesn't fit, THEN create a new story around that small little thought you had.
That's how I create my stories.
In my case I tend to go for really big stuff, like epics, so I'm kinda used to, now, to the biggness of an idea. I don't feel like "Oh, God! Forget it!"
It's actually a challange that I want to explore and try to make the best of it that I can.
All my stories are about stuff that I would want to read about. The story goes the way I want and all of that.
Don't think to yourself "I have to write a story with vampires and teenagers because that's what published at the moment." or something of the sort.
Go for YOUR OWN stories and interests.
It could be that you feel bored of an idea because it's not really using what you like.
And the good news about being a writer is that EVERYTHING in the story you write goes YOUR way.
When you like the stuff in the story, it's hard to let go, lol.