Is this my period or something else?

I was meant to start my period last Thursday but it started on the Tuesday (2 days before). I’m now on day 10 of my period and it doesn’t seem to look like it’s going to stop. It was light for about 5 days, more like spotting and only really there when I wiped. Then it’s been heavier for the last 5 days and I’ve been seeing more blood on the pad. I usually have a normal cycle with my period lasting 7 days. I have been having sex over the past few months without protection and I’m not on any birth control. I’ve been feeling nauseous over the past few weeks and very tired for the last month or so (I don’t know if this could just be due to having a busy life). I’ve had slight cramping and lower back pain over the last few days, and my boobs are a little sore to touch. Is this just my period or could it be something else?