Noticing Newbies

I write science fiction combined with mystery. The stories (I've drafted several) started as shorts, but I was told I was trying to tell too much in too few words, so I've expanded most to between 8,000 and 10,000 words. I don't know if that's too much to be read at once, so haven't put anything into my portfolio yet. I need critiques, comments, suggestions, anything that will help make the stories better. I did have one story (actually under 7,500 words!) published on-line last year, which gives me hope. The stories also are a series, setting the stage for a novel I'm working on (and off and on and---)