Just Wondering?!?!

My fiancé and I have been ttc for a month now! I was supposed to start October 4th! Like always I started spotting but it was brownish the day before Af! Normally my flow is either really heavy with a few light flows here and there! But I am only wearing a panty liner here it is two days into my Af and it's still just really light brownspotting which is not normal for me at all! I've took a pregnancy test but it was Bfn! I'm wondering if anyone else has ever gone through this and what your opinions are! Should I see a doctor?