Question- OPK??

Hey ladies! My husband and I have been TTC for 5 months now. A couple months back I took an opk daily and never peaked ( clear blue advanced). It was only high for 3 days then went to low...if that makes sense? So last month I decided to just do my temp and not stress myself out over the OPKs. Well since nothing came from that, i went back to OPKs this month. I took one on Wednesday it was low, yesterday was high, and today It was low again...? I had to start a new pack of them, could that be it? I also just read to not test in the morning...which is what I’ve been doing. Should I switch to the afternoon? I’m getting flustered! I know a lot of doctors won’t see you if you’ve only been TTC for a couple months. So I decided to try you lovely ladies out! Thank you ladies!