IB or period?

My cycles are regular and they are 31-32 days long. We are currently TTC baby #1 this is our second month trying. My period is six days late and three days ago on CD 35 I had very very light pink when I wiped. it was barely there but noticeable. I had cramping on CD 35 and the past few days more like a dull ache. The past two days I feel like a pulling like I stretched a muscle in my lower abdomen. Something just doesn't feel right like pms. I took a test yerday morning and it was negative. could I still be pregnant?