Help?

Okay so I've just started sex and every time we use protection (condoms). Afterwards we make sure the condom hasn't broken or anything. Anyways, 4 days before my period I bled for a little (beight red, not pink or brown) and then it stopped after a day. My period was due 3 days ago and I still haven't gotten it. I'm showing signs I normally do when my period is coming but those are also signs of early pregnancy I guess, sore boobs, constipation, acne. All I'm wondering, does it seem like I'm pregnant, should I buy a test?