Pregnant or just late..

Elizabeth
I need some help!! I should of started my period on the 13th but have yet to start.. I took a test on the 19th and it had a real faint line saying I'm pregnant, took another one the next day with a negative, then just yesterday I started spotting and now I'm spotting but also have alot of blood clots too. My breasts have been pretty tender and I have been cramping on and off but it's been pretty painful at times. Can anyone give me some advice?!?