could I be pregnant with these statistics possibly? -I will take a pregnant test when I can dw

When my period came it's meant to last six days , it was light at first (but that's normal) then it was normal then the third day brown and light!?!? And then the fourth it just stopped... As its a few days before my period and my cycles are quite long I think I was ovulating but I'm not 100% I just had discharge that day. Also fertilisation takes some time so could I still shred my uterine lining During fertilisation and be pregnant? Hope this makes sense, please help!!