I went to both this board and the pink and got so much support that I did not lose my mind.
You might want to post on the pink board as well. Although many of the ladies there visit this board as well, you might be able to get some perspective on the size of your SCH. You can also hear the dozens of successful pregnancies that happened in spite of bleeds.
I am glad that you saw the sac and that the doctor was able to give you some assurances by measuring the baby's heartbeat. I am an advocate for calling your doctor for anything that really concerns you, so if you do experience more bleeding with cramping and clotting, don't feel silly calling the doctor. I know that I did, and they never made me feel stupid or alarmist. You have worked hard to carry your baby, you don't want to take any chances.