Very positive ovulation test 7dpo with negative hcg test

I’m not actively trying for a baby and I track my cycle as a form of birth control, I do this using LH strips and temperature checking. I confirmed that I ovulated 8 days ago from tracking my cycle and positive ovulation strips, my ovulation strip today has come out VERY positive which I’ve never had at this point in my cycle, usually the second line is barely visible at this point. I did some research and apparently LH tests can spike as they catch hcg before a pregnancy test, so I took a hcg test and it’s completely negative, we did have sex the day I ovulated but he pulled out (I know this is not always effective). Are their any other explanations as to why my LH could be so high?