Question about LH levels and early pregnancy detection!

So I’m about 7-9 dpo and I took an opk yesterday just to see if it would show up as positive because I know those can predict pregnancy. Anyways, I know that you’re not technically supposed to use them because LH can be high regardless but when I took the test yesterday, it wasn’t positive but there was a line there that was slightly lighter then the control line. Does anyone know, or have experience with using an opk to detect pregnancy? Like my main question is can LH be low in early pregnancy and just progress later on? Or would it be high 7-9 dpo?! Thanks