Makena shot

So I just found out at what I thought was 35.5 weeks is that I’m really only 34.6. According to my last menstrual cycle my due date would be October 1st but according to ultrasound it’s October 7. I found out cause I switched doctors and all along they have been saying October 1st until now.. anyways I take the Makena shot and my last one is next week. Has anyone ever just skipped the last shot?