Cycle day 40... 9 days late... BFN!!!

surely I'm out this month and my body is going into some sort of messed up mode... I took an OPK just out of curiosity and it showed a faint line? What does this mean? Urgh so frustrating I'd rather AF just come and go so I know where I stand!!!! When should I think about going to the doctors? Please comment!!!! Going insane 😩