Advice?

So, I'm not too sure anyone will be able to help or give me much ideas (besides a doctor for sure) but oh well.

I usually have really heavy & regular periods. I also have endometriosis, so i usually have a lot of pain with my period too. However, I did have unprotected sex a couple weeks ago (while I was ovulating at that) and a few days ago I started bleeding. (6 days before my expected period) At first it was brown & light pink. Then it got a little redder, and I barely had any cramps. Now like I said before, my period is ALWAYS heavy & painful. I usually get sick the week before I have my period too. The bleeding was very light and lasted 3-4 days, where my period usually lasts 5-6 days (I know that's not much of a difference but oh well) my breasts have been really tender lately & I know could also be a side effect from my period. I don't know, I may sound weird but this just doesn't feel like my normal period. 

Basically, I'm just curious about if there's even a possibility I'm pregnant? (Obviously there's a chance, but I mean like a likely chance? I guess?) Has anyone bleed while they were pregnant before? I've miscarried in the past, so I know it's more than likely not that. 

Is it normal for your period to come early when I'm 21 years old & it's been regular for years?

I don't know why I'm blabbering I'm just curious if I should take a test? (& when?)

Anyways, if anyone has any advice I'd really appreciate it!! Thank you. 😊