Period is a week late ?

I was ually active up until like 2 months ago. I used to take the pill while i was with him except for the last month or so of our relationship we used condoms ( so i quit the pill around 3 months ago ) . After the last time we had I got my period at it's normal time. Now I've been waiting 5 weeks and still no period ! I thought twice that I felt menstrual cramps and back pain , plus I've had a lot of clear discharge but no blood. Is it possible that I'm pregnant ? I was nauseous today out of the blue and almost vomited. However I did just start kickboxing recently and have had some stress. Could those be causes for my late period ? help ! thank you