So, my boyfriend and I had unprotected sex about two weeks ago and used the withdrawal method. Well, my period was about 2 days late and then I started getting very very light blood, basically only when I wiped or went to the bathroom. The next day it was a BIT heavier, but still not as heavy as my normal period and that only last 1 1/2 days. After that I thought my period was done, but that night I saw brown when I would wipe. That was 3 days ago, now all I have is light brown spotting. Could this be implantation bleeding? I took a HPT yesterday it came back negative, but I'm pretty sure it's too early to tell. I've also been very achy lately and my boobs magically went from a 32A to a 32B.

Could I be pregnant?
My boyfriend keeps saying that there's no way that I am, but I just have this gut feeling that I am.