I had the same question and did some research and found this page which explains the length of different works from micro- fiction to epic novels. I hope it helps.
If I remember correctly, the max end of short story is 7500 words which is good since I am close to that. I can’t trim it anymore nor can I add enough to make it a novel and I also read somewhere that novellas are not popular any longer. I am sticking with the 7500 limit. Hope this helps.