No problem :) So what I would do in your situation is stay in the middle. If you O'd between CD18 and 23, I would mark it to be CD20 or 21. If you wrote down symptoms and other details, it may help you choosing the date.
The LMP calculation is based on a 28 day cycle and assumes that women ovulate 14 days after they begin their period and they count pregnancy from the first day of your cycle. This means that at CD14 you are already 2 weeks pregnant even if you haven't ovulated. If you ovulate on CD21, you are already 3 weeks pregnant.
I personally shave off that two week discrepancy by marking my LMP as my Ovulation date as many other women do. Even then, there is no guarantee that baby will come at 40 weeks. Baby may arrive at 38 to 42ish weeks. So in my case, I should expect baby's arrival from Mid October to mid November.
Here is a very nicely written explanation on due date calculations:
https://spirited-mama.com/tag/parikhs-formula/