Spotting vs. period - when to take Femara?!

Hi mamas. I took Femara to conceive my daughter 3 years ago and it worked right away. This time around, I have taken it three months without a positive, which I understand happens, but my period is definitely different since I had my daughter. Sometimes I will spot for days in advance before having my period. Take this month for example. I tested to see if I was pregnant from the 1st until today, all negative. I spotted a tiny amount of red blood on the 2nd at night, and then had a little bit the next day in the morning, but nothing since then other than some brown, dry blood when I wipe. Still haven’t started, no cramps, etc. Since you have to start the pills five days after you start your period, I am wondering if I’m taking them at the wrong time because I’m confused about spotting versus period. I asked my OB and he wasn’t clear. I just need some advice… anyone else have this issue?! Help!!