I am 12 dpo. CD 28. I haven’t tested for a few days but they have all been negative so far

. All I have left for pregnancy test is my frer which I am saving for tomorrow morning. AF due anytime. But because I don’t have any cheapies left I used an OPK. Is it common for a test to be this dark right at the end of my period? Or could it be picking up hcg? I cant tell if my symptoms are PMS or preg. Anything kind helps me feel better regardless of the answer. I hate not knowing blahhh.