Choosing doctors at KKH

Hi, I am 12 weeks pregnant (PR in SG). Have been going to KKH under subsidy. Next appointment will be on 15th and 20th weeks. I understand that if I chose a specific doctor then I would be treated as private and so no more subsidy from that point onwards. 1. When will I be able to choose a doctor? 2. How does that procedure go and what are the costs like? Is there a maternity package I can sign up for in KKH itself? 3. Will I be given a list of doctors to choose from? If you have been through this before please help to clarify. Thanks 🙏