Poked myself with a needle in the Gym M(18)

Yesterday I had the late shift at the gym where I work, and while emptying the trash cans, I accidentally grabbed what was probably a used hypodermic needle. The wound was bleeding, so the needle must have gone through the skin. However, there was no visible blood on the needle. I don't know how long the needle had been there because the trash can hadn't been emptied for two days, so it could have been anywhere from two days to 20 minutes old. What are the risks? I have a doctor's appointment tomorrow for a blood test, and the wound doesn't look infected (slightly red and not oozing pus). How realistic is the risk of infection, and how reliable will tomorrow's test be in the long term? If the doctor tells me "you don't have an infection," can I really rely on that, or do I need to wait for further tests before I can be sure?