Wrong doctors

Ive been on birth control for about 3 years and i was on the pill for a year and then switched to the shot with no problems. Of course until yesterday when i went to get my shot and they say they accidently scheduled me wrong. I was 6 days late for it, meaning i could be pregnant. I have to wait to get my period in march. I literally almost cried. Im 17, i cant afford for people to make mistakes. This wasnt even my fault. I just hope im not. I really should sue the doctors office. What do you guys think?