You don't say anything about having unprotected sex during this cycle. The spotting you started does sound like a period, though. I can help you out more if you tell me about the protected sex.
dizziness, nausea, etc. are also PMS symptoms or can be associated with so may other illnesses including cold, fever, flu etc., so one cannot really say if one is pregnant, just by those. Why don;t u also do a home preg test a day or so after your period is supposed to start?