How can I write a sophisticated story for English AS?

After weeks of writing a narrative for my English AS coursework (WJEC), I've have been told that it's excellent by one teacher (who has previously said the same about stories who have been graded poorly) but of low quality from another (who has, in the past, been a fantastic teacher).

I decided to write my narrative using the first person, as I want the reader to have direct insight as to what the protagonist is feeling. However, this 'doesn't allow the reader to do any work'. I've repeatedly asked the teacher who said this what she meant and how I could make my writing a little more sophisticated. However, she only suggested I actually give less description in terms of the protagonist's emotions, in order to prevent my readers from being spoonfed information. Nevertheless, I feel incredibly lost now - I don't know where to begin re-writing! Any ideas?

I'm hoping to receive an A, so I would appreciate any advice people have!

Thank you