Jan.17th Conception date/due date confusion

Hey, needing some feedback from other women that may be around 15 weeks along.

My LMP is unknown, as I never keep track (they are always unremarkable) however I know that the EARLIEST I could have conceived was April 23rd. Both my OB and the pregnancy app calculator added on approx 2 weeks to my gestational age and I am now between 15 & 15/4 weeks gestation. My initial due date was Jan. 17th.

For some reason these numbers/dates seem really off to me. Is anyone else around the same gestational age as me and can weigh in on their due date estimate? Thoughts?