I just started two months ago and am still with my preceptor. We (I) pulled morphine from the pyxis and gave the correct dose to the patient with her watching the whole time but we forgot to go back to the pyxis and waste the remaining in the vial. I discovered after an appointment that I still had the remains dose in the vial in my pocket. So I returned to the hospital to waste it properly in the pyxis with another RN. We reported it to the manager of the unit and I wrote a note about the situation and exactly what happened. I am so worried that I will be fired over this situation.