Help please

Lia

I took a cheap pregnancy test (Walmart 88 cents) today and it gave me a bfn.... I’m assuming that I’m out for this month? Af is due Saturday I’m praying I still have a chance but quite doubtful after that bfn. But what do you ladies think do you think I have a chance still? And if you think I’m out for the month please advise me on how I can ensure or at least rise the chances of conceiving October.