I recently shot on a fresh roll of film using my Olympus OM-1, everything seemed to be working until I rolled up the film. The film came out a little bit (I'm aware any of those photos are ruined now) and it was completely blank. it looked the same as if I didn't use it. I've tried looking it up but the answers vary from it doesn't show up until developed to your camera is broken. It didn't seem to be broken, everything worked from the shutter to the timer. But it was second hand so it may have been broken? How do I know for sure my film has been used?