Could this Implantation bleeding ?

me and my boyfriend had unprotected sex alott Last month and he ejaculated alot of times butt I don't know ? Could I be pregnant? I got spotting one day That it you could hardly see it on my undies ,the next day it was heavy for 2 days and the next day it was so little that I didnt need to put anything it was just when I wiped and the next day it was light? I never had a period like thiss . I just want to know if I'm pregnant or not.