Keep changing my due date


So because I am on heart medication Fetal Maternal Medicine are having me in for more ultrasounds. At my anatomy scan they changed my due date from 1-17-18 to 1-16-18 no big deal only one day, but my last scan at 29 weeks they have now changed it to 1-10-18. I dont understand why they keep changing it, hes measuring ahead, I get that but I am getting annoyed. They also said they want me induced at 39 weeks, so I was asking my husband does that mean around 1-10-18 or is it going to be 1-03-18, if were up to me my due date would stay on the 17th. Anyone else experience this? With my 2nd I was high risk as well and Fetal Maternal Medicine changed my due date but only once, they changed it from 12-22-15 to 12-14-15 and she actually came on the 14th. Im just getting annoyed.