It is normal for menstrual flow to vary from cycle to cycle, and this is true even if you have an established "regular" period generally. It sounds like you are having a heavier period than usual, and no this would not be caused by pregnancy. A period of 7 days or so is still within the average duration of a period. Cramping, too, can vary a bit. If you've been experiencing extremely heavy flow (where you have to change pads, tampons or cup more often than every few hours) this whole time or your cramps can't be addressed with over-the-counter painkillers then you should see a doctor, however that sounds like it's not the case for you in this situation.
You can read more about it in this article here: On the Rag: A Guide to Menstruation
But essentially lots of factors can influence menstrual cycles, including rest, activity, how and what we eat, stress, being unwell.
Speaking of stress, you've been asking a lot of these questions about pregnancy lately, how are you doing at the moment?