Is Aunt Flo playing a brutal trick or do I still have a chance this month??

I'm not 100% on my ovulation but AF is spouse to start today or tomorrow. Yesterday around 6pm I started having light spotting mixed with CM. I did not have implantation bleeding with my first. I have very regular periods that start light but quickly increase and only last 4 days. Can anyone tell me about their experiences with implantation bleeding. I'm at a loss ladies, not ready to give up but scared this is just an off AF.