Unsure on what's happening

So I had my period on the 2nd of Jan, but a week before that I had light blood when I went to the toilet. 

Now I finished my period on the 7th of Jan. And I've been having bad cramps within the last few days And sore breast/nipples.  I had unprotected sex in my fertile window, I want to do a test but I'm unsure if I should just until I'm due for my next period. 

please help!!