Q) miscarriage; the amount of blood

Kim
Hi, I cannot see a Dr before Dec 1, so I'm writing here.
I was 7 week+0 day yesterday after trying for 6 months after Mirena Removal after my 1st baby. 
Yesterday around 5:30pm I was potty trained my 1st baby and I sat on my chair and I felt gush on my panty. Rushed to toilet, my panty was wet with bright red blood with mucousy look amount of 2/3 panty liner. Thumb nail amount on a seat was wet with blood.
After that, I put menstral pad on my panty, I find only dark blood; spotting on my pad- very small amount like baby pinky nail amount from last night. I just wiped after pee, and dark brown color; old blood look&stringy came out after only my second pee of day today.
No more significant amount of bright red since yesterday, but is it still miscarriage? Anyone had this small amount, one time bright red&amicus discharge as a miscarriage?
I have dopper at home, will it be heard the heartbeat at this early time of 7 weeks (if baby is still there)? 
How long will I feel this nauseous feel even after miscarriage?
Thanks all! I appreciate any answers!