I'm 21 weeks pregnant (in Dallas, TX) and I've had no prenatal care due to having no insurance....?

Now that my insurance has kicked in, I've been frantically looking/calling everywhere for an OB that will accept me....I've called and called and everyone keeps telling me no one will take on new OB patients after 20 weeks gestation. Is this true? How can that be? What shoudl I do? Should I lie about my LMP just to get in the door? I mean I'm really freaking out (if you can't tell) Someone please help?