Confused? (Sorry tmi)

My husband and i are ttc. I took a pregnancy test 2 days before my period was due. It was negative. That same night i started what thought was my period Brown stopping. Its been 4 days and its still just lite Brown spotting. Barely enough to fill a liner. Its should be full blown period by now. Has this happened to anyone? Should i test again or is my cycle just messed up from ttc?