Cd48, 21 days late, bfn

Hey girls. So I'm a very regular 26 day cycle and I'm currently on cd48. I have had no change to diet, exercise, lifestyle. Multiple pregnancy tests have been bfn, as well as a blood test which was taken at 2 weeks late. I had spotting yesterday and the day before, which was literally a tiny amount of brown discharge just in the morning, and nothing the rest of the day. Anyone in the same boat or have some insight? We have been ttc for about 20 months, and have now been referred to a fertility doctor and I'm starting acupuncture on Monday, but I'm kind of crossing my fingers that I won't have to do any of that!