Haven't you heard? Even Harper Lee had two stories in her. So, apparently, you're not alone.

I get what you're saying about taking time, but I just can't do that. My problem is, if I don't write the story quickly enough, I start to forget the details from earlier in the story and I don't close plot threads, or I write things that conflict with one another. The outline helps, but I'm even talking about small scale things.

Cheers,
Michelle