I'm in Missouri, so it may be different out here, but its not absolutely common for OB's to REQUIRE a U/S to confirm pregnancy, although many offer it. I know you feel crunched for time, but another week or two wont do any harm if you're still looking for a provider. US maternity care is super ovrrbearing compare to other countries, having women come in as early as 4-6 weeks to initiate care. That's way too early and unnecessary. Buts that's how they do things.
I second what the PP poster said about checking your tribal area for recommendations for an OB.