OD changed by 5 days in month 2 TTC

So I only started tracking and using an OT last month and during our first month of TTC I got my peak on C18. Naturally I only started testing yesterday (CD12) with the advanced clear blue test to target our high and peak LH days. Well when I tested SMU yesterday it was negative, which I expected. Well this morning I'm testing and checking my phone totally not thinking it would be positive and I'm already at peak on CD13. What the snap? I checked with both tests to make sure. I'm glad we BD yesterday! We were going to do every other day and then everyday for the 4 most fertile days! Guess it will be today and tomorrow and maybe the day after. Really hoping I didn't miss some BD earlier! So glad I started to test. BABY DUST TO ALL!! Hoping this is our month ❤️