Miscarriage question.

Is there any way to know for sure if you had a miscarriage when your pregnancy had yet to be confirmed? I went to the doctor's last week for a blood test to see if I was pregnant because I was late and having symptoms. However, before that (I can't remember what day), I'd had worse cramps and more bleeding than just a bit of spotting. The test was negative, but I can't help but wonder if I'd been pregnant and had a miscarriage. I would've been about six weeks along, if that helps any.