Miscarriage Answers?

Janey • This frikkin` lady.
So, I could be wrong, but this is my story; please let me know if you have any advice or think it could be something else. 
I was 8 days late on my period this month; all home pregnancy tests read negative. I don't have any health issues, no stress, no change in my diet, nothing. Cervix was high, closed, and soft through all of it. 
I received my "period" on the 9th day of having a missed period, which came with these awful upper abdominal pains and pain in my lower back (this is what made me assume it was a miscarriage, and I had noticed my nipples had become darker; I assume it wasn't very far along, as it didn't register on a home pregnancy test.) I passed little bits of tissue; nothing really different than a regular period. 
Seven days later, all was cleared up. I did have sex with my husband at that point, and the next couple of days. So it's been five days since it all cleared up, and yesterday I felt a little cramping, and today I have cramping and a little spotting..I had made a Doctor's appointment, but they can't get me in any sooner than the 12th of August..
Is this a bad sign? Normal? What? I'm just at a loss, and my hormones are kind of all over; have been from the past month..