Bleeding is different than spotting. Period. You have tested negative for pregnancy, therefore what you are experiencing is not related to pregnancy. Spotting is, well, spotting. It is NOT like period bleeding. It is the bleeding that is only there when you wipe, or maybe only a drop or two in your underwear. It is, essentially, spotting. Bleeding is considered like your period, where it lasts for days.
HCG = the hormone that pregnancy tests pick up and also what creates pregnancy symptoms. HCG is detectable in your body 10-14 days after conception.
Miscarriage is the loss of a pregnancy. You would still test positive for pregnancy for a few weeks after a miscarriage. Since you have not tested positive for pregnancy, you can not be miscarrying.