Confused

I'm not sure if this is the correct group or not but me an my fiancé have been ttc an it hasn't happened yet i just had a normal af 8/12 to 8/16 I woke up this morning with him for work and had no spotting no nothing I laid back down for a few hours then when I went to the bathroom I was spotting a very light pink however it's not enough to get to the pad I'm wearing i only notice it when I wipe the past few days we have been doing the bd due to me starting my fertile window I have never had spotting between my periods has anyone had this happen before or have any ideas what could cause this to happen