greetings Lynsey;

don't worry about this twin pregnancy. once a women go to hospital for
pregnancy checkup and the Ultrasound result confirmed that she was
carrying twin baby and doctors advice for second ultrasound scan in a
month time. on her second scan it was observed that she was carrying
only one baby. the confusion comes from the interpretation of the
ultrasound that it was the big amniotic sack(bag) who seems twin. so
it is a good idea to make sure that it is twin by taking another scan
the time the fetus is approaching to some 20 weeks.