My girlfriend got the depo shot on 6/17/2014 after several negative pregnancy tests. We decided to get the shot to protect us against unwanted pregnancy, and also she was several days late from her period. She has a history of irregular periods due to her active lifestyle. She was experiencing very light spotting the day of her shot, and her bleeding did get heavier several days after. On the 5th day after her shot, we had unprotected sex, and I did finish in her. She also stopped bleeding come the 6th day. Does the light spotting on the day of her depo shot indicate that her period started, and does it protect us from pregnancy?