Can someone help me with these please soo confused!!

Samantha

Hi ladies I did a test yesterday afternoon which is the top test that has a faint line on it. I have no idea what DPO I am and I’m due on my period in about 8 days, I did the second one down last night and the last one this morning. I’m soo confused how can hcg drop just like that?? I really need some advice. Thanks 😊