Different Calculations of Due Date?

R

So, I just found out yesterday that I'm officially pregnant (yay!) and Glow and Ovia are telling me different due dates. I'm pretty sure Glow is basing it on my last period start date (March 17) and says that I'm 5 weeks and 1 day. Ovia is, I believe, basing it on ovulation date (April 8 is when I got a positive opk, so probably April 9?) and says I'm 3 weeks 5 days. Which is accurate? Or do I just need to wait for my first doctor's visit? Thanks!