I'm trying to create an ERD in Microsoft Visio using the following business rules. Does my current diagram look correct? Am I missing any relationships or Foreign Key fields?

Patient makes an appointment to see a doctor

The appointment is for a particular date and time

The patient is assigned to a doctor but if this doctor is not available, the patient is allowed to see the other available doctors

After treatment, the patient makes a co-pay payment

The patient is insured by an insurance company

The insurance company makes the remaining payment

Appointment Doctor Patient AppointmentNumber int Doctorid PatientiD int Appttype Varchar DoctorFirstName PatientFirstName Varchar ApptDescrip Varchar DoctorAddress int DoctoriD int Insurance Company Payment int InsuranceColD int PaymentiD PaymentMethod PolicyNumber int CreditCardNumber PatientiD int CreditCardExp nsurancecOID PatientiD