Miscarriage????

I was 8 days late so I took a pregnancy test which came back negative , two days later I got what I thought was my period, usually I have an extremely light flow (so light I don’t even feel it and have never leaked out of a pad) but this time it was leaking all down my leg even with a tampon and a pad so extremely heavy! I have been bleeding for 6 days now and have been experiencing extreme cramps (something I don’t usually have) and back twinges. Then this came out. Do you think this is a miscarriage? If it is I would’ve been 5 weeks pregnant. Please give your opinion .