Need Advice - Could i potentially be pregnant or am I just over thinking?

Dennea
A week, maybe a week and a half  ago I experienced some dull cramps in my lower abdomen/pelvic region around where my ovaries are a few days after my boyfriend and I had unprotected sex (we always do), and I didn't think much about it because I was tracking my period and new i was supposed to be expecting it in the coming week/weeks. Well I ended up spotting/having what I thought was just a really light period early on the 15th and didn't think much about it. but Monday it was like a really really light flow and at first a brownish color which a chalked up to old blood, but then later was a lighter pinkish/red color. and yesterday, Tuesday, it was so light that when I went to change my tampon it was difficult to remove. Now today (the day my period is supposed to start according to my charting) it seem like any type of flow/spotting is gone. And The last two periods I was using super absorbency for all 5/6 days. Plus I didn't have the same cramping/constipated feeling that period cramps give you. And that's I really realized and thought about the fact that this spotting had come 3 days earlier than my expected flow and I have never been early,b even when I was on bc I would be halfway through my placebo pills before getting my period, but I was never early and when I haven't been on bc and have paid close attention to my cycles I was either on the day of or the next day. Also have never had so little blood for a period. When not on bc I get killer make me want to rip my insides out cramps with bloating and bleeding like someone slaughtered a cow and these symptoms are no where near anything like that. I think my nipples are darker too but I don't pay attention to them enough to really know. I have been extremely fatigued over the last couple of weeks, even just putting my hair in a ponytail makes my arms and body exhausted. Am I just over thinking and  imagining it and that was my period or could it be implantation bleeding? Is it too soon to take a test? I don't want to jump the gun on it. 
Update: Today there is no visible spotting in my underwear or on the toilet paper when wiping. I only realized I still had some spotting because I stuck a bit of toilet paper inside to see if there was any remenants. There was some pinkish red blood but it's not thin or thick enough to fully discharge or expel itself from my body so there's not really a "flow." I'm just freaking out and my boyfriend just makes jokes because he already has two kids and doesn't think it's a big deal. Can someone give me some advice.