Did I miscarry?

Anna
I had sex with my boyfriend on May 5th, and we didn't use a condom. It was the day I was most fertile and it's now May 11th and I have been showing the earliest signs of pregnancy. My breasts are sore, my back hurts, I'm insanely moody... I even talked to a woman at planned parenthood on the phone and she said that she thought I had implantation bleeding when I explained to her my brown spotting. I was set to go get a test as soon as I missed my period which was scheduled to start on the 18th, but instead I just woke up at 4:00 in the morning to the heaviest bleeding I've ever had. It was as if I had my entire period in one minute. The odd thing is, there was no "passing of tissue", it seemed to be just normal clotting like I was on my actual period, but ten times heavier. I also had light cramping that is still persisting. So why did it come so early, even when I thought I was pregnant? I'm worried that I either miscarried or there is a health issue that I'm unaware of. Even though my status is trying to avoid pregnancy, I got used to the idea that maybe I was okay with it. I feel quite crushed and any insight would be greatly appreciated.