Confused!!

Tab
I had spotting on the 14 & the 15th. It wasn't enough to fill a pad. My last period was June 8th. I have had an ultrasound about a year ago and I do not have any ovarian cysts and my periods have been irregular, but anytime I spot my period is usually right behind it and nothing! I have taken a test and it is negative. Has anyone else had this issue?? I don't think I am pregnant but you never know. I just wanted some opinions! Thanks ladies and baby dust to all of you!!!