How Do I Know?

To start off I became sexually active last September at the age of 16, I refused to use birth control because it wasn't a situation where I was constantly having sex, it was rare. Once I turned 17 the intercourse became much more often than before but not so often probably like a monthly situation or most of the time two months go by. But I had scares I was paranoid of getting pregnant so I decided to get a form of BC; I did research for months until I decided to go for the Copper IUD and once I went to have a consultation I wasn't recommended the Paraguard because I was anemic instead it would be best to go with the Mirena, so 2 weeks later after the consultation I got my Mirena inserted (12th of July). Ever since then Ive been getting cramps and have been spotting, Ive had clear discharge much heavier than usual. Everything pointed to what the doctor told me to expect. Except today, I had the usual cramps, but the spotting had been I guess you can say more but not heavy enough to worry, I checked for the string it was still in place so I thought it could be my period but my Period is due in 8 days. Could it be ?