Brown spotting instead of full blown period

Lauren

Anyone had this happen? I’m supposed to be on day 4 of my period but I’ve just had light spotting. My boobs usually stop hurting once my period comes but they are still super painful to touch. Usually I get maybe 1 day of spotting or a few hours of it and then the full period comes but it never happened this month. We’ve been TTC for a few months and I took a test two days ago that came out negative.

Any thoughts?