First Appointment/Due Date

Lindsay • Married 8-9-14 Baby #1 Born 1-26-16
My LMP was 4/23 with 28 day cycles. I went to my first doctors visit today for pregnancy confirmation. 
The nurse entered my LMP into a computer and told me I was 4 weeks and ? I forget days pregnant and due Feb 3... I don't get how she decided this. Every <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">due date calculator</a> and just counting on a calendar says I'll be 6 weeks on 6/4 and due 1/28. Just a little frustrated with this "due date" and thought I was well... A little bit closer to being out of the first trimester. 
I'm sure the due date will change as we go but I didn't like this news today- doesnt make sense to me.