do I need to tell my doctor I want an elective ultrasound?

Mama
I've never had a pregnancy were I only received one ultrasound at 20 weeks my last two pregnancies I was high risk and had a dozen. We want to pay for our own and of course if I could get my doctor to order an ultrasound and my insurance would cover it that would be even better! But how do I go about telling my doctor we want an ultrasound to check on the baby even though she doesn't think I need one?