Pregnant?

So my period wasn't suppose to come until the 4th and they usually last about 7-8 days. Well when I started on the 1st I just thought okay it's a little early. But when I start I am a really heavy bleeder and this time it wasn't near as much as my usual! And then for three more days I was just spotting? Like throughout the day randomly. I would go to change my pads and most of them had nothing on them. I read up on implantation bleeding and I'm thinking maybe that was it? We had sex in the window of implantation bleeding so maybe?  I'm scared to take a test because I don't want to read another negative. Any thoughts? This ever happen to anyone with positive or negative results?