TTC and confused!

Hi all! I am currently 8 days late (CD 50). Last week on the day I was to start, I started having period like cramping and lower back ache. It went away after a few days. Yesterday morning got a BFN. Last night my back started aching again. Still no AF. I believe I am pregnant, but I’m wondering...has this happened to anyone else? I’m getting very discouraged by all the negatives..I contacted my OB and she told me I needed to wait for a positive hpt. My husband and I are so anxious to have a baby! 🙂