implantation spotting?

i was supposed to start my period yesterday but my period is sometimes late. i am approximately 14 DPO and possibly could have conceived anywhere from 15-20 days ago. my breasts are slightly tender, i have some light cramping and bloating. im not sure if i usually spot or not but if i do then its usually followed shortly after with my period (maybe an hour or so). i took a test and got a blood test 4 days ago and it was negative.

i have been spotting since late yesterday off and on and still spotting today.