Inplant

Good evening ladies I'm going to become a first time mom.I am 22 years old. I was on the inplant for 2 nd half years than became pregnant. I went to the clinic nd they told me at the time I'm almost 4 months..somerime in last week I went to the hospital for sonar nd they said my edd is 20 feb 2020 nw I'm totally confuse...