Not sure what to do

Hey, so my boyfriend and I have unprotected sex all the time. Yah, people don't condone it but we only sleep with each other and he's the one I'm gonna be with for a long time. So therefore, back to the story, we had sex about 3 1/2 weeks ago or so. Maybe longer, I'm not positive but I'm havin symptoms like I could be pregnant. I'm going to get a test but what are some of the symptoms y'all had when you first were pregnant? And another thing, I had my period but like it wasn't normal. It was really light and only lasted 3 days. If that. So could that have been implantation bleeding? Like. I'm just trying to get a better understanding of all this.