"Period" came on time but not normal

My cycles are 29-30 days and have been very regular for years. My last regular period was August 17th. AF arrived on September 15 as it was supposed to, but I only bled for a day and spotted the rest of the 5 days. I took a test 2 days ago(9/29) and negative. I have been feeling pain on and off on my left side below my waist. I feel very bloated and full for a couple weeks now. I don't have sensitive boobs or really any pregnancy symptoms. What to do? Could I be pregnant? Need advice...