Missed miscarriage

Anna
Is it very common to have a missed miscarriage after hearing the heartbeat? I had an ultrasound about a week ago at 7w2d but had some spotting on Monday (brown and stopped after an hour or two) and just haven't felt very pregnant. Dr said it's all normal and I won't get another ultrasound until 12 weeks. I wish I could get one every week for reassurance.