I use cheap opks and a wearable device to monitor temperature. This is my first full cycle after giving birth (mid February) and I am not breastfeeding anymore (stopped mid April).

I got a really strong positive opk result on days 8 and 9 dpo with a temperature drop (haven't opk tested for day 10 dpo yet). I checked for pregnancy but tests came back negative on those days. As you can see we didn't have sexual activity on the days when I might have been fertile, so I think the chances for a pregnancy are low. Also, I think the temperature is quite accurately taken (I do get more than 3h of sleep at a time).

What could be causing this opk result? Do you think the ovulation date is wrongly identified? Do you think it could still be a pregnancy but I tested too early? Or am I just hormonally messed up and should ask for expert advice as soon as possible? Any plausible explanation is welcome and I will be grateful for it.