Is it implantation bleeding? And how soon can I take a test to know for sure if I am pregnant?

It's been a while since I've consistently took my pill, about 2 weeks, unintentionally from stress and more after me and my love broke up. So my last period was Dec. 24th and ended the 29th (exactly two weeks ago so it hasn't been long). Me and my love did "it" the very next day and about 6 to 7 days later I've had slight to very ligjt cramping and very very light bleeding, light pink to brown, on the 2nd or 3rd day of it now, somewhat like implantation bleeding that I've read on. My next period isn't supposed to start until next Friday the 17th. I'm just wondering what could it be and if it's a possible chance I may be pregnant and when should I take a test? Also me and my love broke up two weeks ago but still saw eachother and spoke and I brought it up to him and he was opposed saying I'm just saying this so he can't move on, but that wasn't the case, honestly I want us to work on things together and eventually become a couple again, I believe and know in my heart that he's the one. We've been together for 4 years and dreamed of having a family and stuff together so I would think he would be happy, but he's at the first stage after a break so I understand why he feels and thinks what he does. Just wish all of this could've been at a better time and we were still together.
Is it implantation bleeding? And how soon can I take a test to know for sure if I am pregnant?
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