What Causes Vaginal Spotting With No Regular Period?

hello there. im 19...last period was october 28th....sat-november 20th i went to the restroom and when i wiped there was a small..a little bit smaller then a pea on the tp...went in today and the doctors done a blood test but never gave me the results...whats going on? why was there just a tiny spot of blood on the tp and nothing else...do you have to wait til after your missed period for a actual reading of the blood test?