PREGGERS OR NO?

First and foremost... no judgement. I don't need a lecture on what I do or don't need to be doing. Thanks 😊 So my boyfriend graduate from Basic Training last week. I am on birth control but was taking an antibiotic up until the day after thanksgiving (Nov. 25) We had sex from Thursday night (Dec. 1) to Saturday (Dec. 3) We did it a total of probably... give or take 10 times. Unprotected and he finished in me. (Yeah you can tell we don't care anymore) I was suppose to start my placebo pill the next day, Sunday (Dec. 4) So I took them. This Wednesday (Dec. 7) I started bleeding. But it was brown all day and still brownish color when I woke up this morning. I was cramping really bad yesterday. I am again today but it's a slight more prominent on my right side. I normally NEVER cramp during my period when I'm on BC. When should I take a test? Or does anyone know this kind of stuff?