Question that needs answers so confused!!!!

I was due for my period on sept 19th.. Took 3 tests and all faint lines .. Well yesterday I started spotting .. I thought maybe it was late implatation bleeding .. Well today it's a full period .. I looked it up said its a chemical pregnancy.. Just never attached itself .. Well I was hoping for a better next month .. But every month since I had my monthly .. I went One day without my period then my fertile window started .. But since I was late this month it's saying I have 4 days without my period then my fertile window starts ...??? I only have 7 tests left for my ovulation kit.. And idk when to start testing :,( please some one help