Pregnant Having Spotting. Vaginal Ultrasound Showing The Baby But No Heart Beat. Greyish Solid Discharge. Concerned About A Miscarriage?

Hi I am 22, will be 23 on the 14th of this month. About 2 weeks ago I took an at home pregnancy test that came back positive, and this week noticed some clotting, spotting which has turned into light daily bleeding for 2 days now. Yesterday in the afternoon I went to EMERG and they determined that I was 6 weeks and one day along. They ran a vaginal ultrasound and saw the baby, but too early to decect a heart beat. I have to go back sometime this week for another U/S but im worried because today while i was going to the washrooom i passed a Large clot like thing- but it sisnt look anything like a clot from my peroid. It was greyish looking looked like a hunk of something. I am extreamly worried and I was wondering if i could be assured that this WAS NOT a miss carriage. thanks