Implantation bleeding or period? what do u think?

I had unprotected around the time i ovulated! I was due my period on the 8th! it did start this day like clockwork...but started very light pink mixed with mucus this was only when i wiped! on the 9th i wore a tampon as it had become heavier but only for a few hours then stopped, and the same happened on the 10th! Then on the 11th ther was barely enough brownish blood to need a pantyliner! could i still be pregnant? I had sore but this has gone...only other symptoms i am having is that im sleepy no matter how much i actually sleep and have light nausea, frequent headaches and heartburn mostly at night!