Do I have to move to March due date?

Bethan • Married 4yrs with 4yr old Boy. Pregnant with TWINS!!! after TTC 2 months. Very nervous about this time after awful pregnancy and terrible labour & birth.
Am currently pregnant with twins due 12th April. Had consultant appointment today and was told they won't let me go past 36/37 weeks. So looks like mid March. Do I stay in this group or do I have to move over to March due dates.