Pregnancy Scare

I'm 17 and I'm scared to death I might be pregnant. Apparently my ovulation ended on a Tuesday(9/26) and I had unprotected sex on Thursday, Friday, and Saturday (9/28-9/30). My period was suppose to start Monday (10/9) but I'm now two days late... I had cramps for one day before my period was suppose to come and now instead of blood I just see a lot of white discharge. I don't have tender breasts nor have I experienced frequent urination but I've never experienced this much discharge and I was cramping so I thought my period would come for sure...I'm absolutely scared. Am I just over-thinking or should I be concerned?