My Doctor is giving me problems?!

I posted a question similar to this earlier but I have another question to go with it. So I'm pregnant but have no idea how far along I am. The clinic gave me a referral for a dating scan for a doctor in my town and it's been a week and she hasn't called me back. Do I NEED to see that doctor because of the referral or can I call any doctor and tell them I'm pregnant and need a dating scan?! I'm really confused and I just want to make sure my little one is okay, and I'm a first time mom so I know nothing about this stuff and it's been stressing me out.