subchorionic hematoma

Anyone been told they have a sch? I’m 11 weeks and had very scant brown/pink discharge yesterday so had an ultrasound today which showed a small Subchorionic hematoma. They said nothing you can do for it and to just refrain from intercourse. They say sometimes if it gets larger it can cause a miscarriage. They aren’t planning to re check it until my 20 week scan. Is this normal to wait that long? Anyone with this and experience a M/C or healthy pregnancy? Anxious mama over here