Weird cycle this month..

So I was supposed to get AF monday, nothing came until Wednesday- but it was literally like one small spot on a tampon. No cramps (mine are normally HORRIBLE) and today- AF is gone completely. Last month, I bled so hard over night I woke up in a puddle of blood- I normally have heavy periods , but that was not normal for me. Any input? I took a test, it was negative as usual... I have an appt with my OB on the 30th.. We've been TYC for over a year now...