On my period(I think) Not sure what is going on. Help PLEASE!!

OK so I am usually a pretty heavy bleeder when I first start my period. For the first 3 or 4 days of it. And usually I have really bad cramping!! This time though, it is VERY light. Like I have been using the light tampons for 4 days. And there is barely any blood on it. And NO cramping! NONE! This concerns me. I have been tearing up at pretty much random times that aren't even sad, (EX. A friend of mine an di went to see the simpsons movie. will I BAWLED during the last 25 minutes or so... If you've seen it you know its NOT a sad movie!) My lower back is sore. But my breasts aren't tender, When I was pegnant last year(had a miscarriage) My breasts instantly started growing and got very defined blue veins. But I wasn't emotional. I had sex a few weeks back, but it was protected. I'm very careful after the miscarriage last year. I don't want to go through that again! Maybe I'm just over thinking things. But maybe something is up? Any advice? ANYTHING would be great at this point! I'm about ready to pull my hair out! Thanks in advance!!