Early Pregnancy signs...please answer if you've had a similar experience?

I know there are like a million "could I be pregnant" questions on yahoo answers and I read them and wonder why people keep writing them. Anyway, well... I have one. Here are the details...I had sex on April 30th. Been feeling really weird...maybe early pregnancy signs, I don't know. I planned to take an early pregnancy test today to see if it might explain the weirdness, but today I am bleeding. It is very light pinkish and makes me think of implantation bleeding as it is explained around the net. This doesn't seem like a typical period and it is 5 days earlier than my period is supposed to be. I took a pregnancy test today and it was negative, but this early, a negative result is only 53% accurate. If its implantation bleeding then maybe i should test again later. If its my period and I am pregnant then it should have come up positive. Has anyone had a similar experience that went either way ( + or -)? I'd be glad to know.