Ttc bleeding two weeks before af is due?

[Jaylady]

My boyfriend and I have been ttc for a few months. I was on the implanon bc for two years and had it removed. When I had it taken out I immediately had the period within a few hours. It came earlier than expected but I assumed it was because of the hormonal changes. For the past few months I have had a regular 28 day cycle. My af is due on the 10th of May but this month I spotted on the 26. A few days prior I had really bad cramps and my body just felt weird. My bf and I had sex two weeks earlier and I immediately felt different. When I saw the spotting I assumed it was implantation bleeding but it got really heavy the next day. My periods are normally light so this was very abnormal. I chalked it up to being my period after I saw all the blood but it was so heavy that I was changing my tampon almost every two hours. When I woke up this morning there was no more bleeding but I am still having cramps on my left side. What could all of this mean ? I did some research and found out that ib could be heavy but mostly light. I took a hpt the day before I started bleeding and got a negative. I know it was too early but with the way I was feeling I just couldn't wait. Now I'm extra nervous and want to know what's going on!