I've been pondering Betsy's excellent comments of Dec. 13 as I work on a short SF story myself. She said to 'Put your story on a diet'. I agree with the intent of this comment, but IMHO the wording is imprecise. You don't want to just make your story shorter. You need to cut out all the non-vital parts to concentrate or distill the story. Leave ONLY the essence of the story, lose the extra bits.
For example, the short I'm working on involves a woman who uses the Transactional Interpretation of Quantum Mechanics to save her family. When I wrote it originally I included this whole thing with Homeland Security (HS). After pondering it for a while, I realized the problem with the story was the HS part was totally superfluous. So, it's back to work for me!
What's the essence of your story? Are there any superfluous bits?