insurance and ultrasounds

I'm awake at 3:45 this morning because for the past hour I have been laying awake thinking about insurance. My dad had me on his insurance since I was 18 (had Medicaid before that) as a requirement he picked for himself that he would keep me covered until I was out of college. Well my dad has continued to keep me covered because it was so much cheaper for him and me to be on his insurance because he was a nurse at the hospital my doctor works in. Well my dad got a job offer and switched to become a traveling nurse. When he did my bitch of a stepmom got insurance on me. She NEVER holds a job. She works somewhere for as long as she wants and then just sits at home all day and expects my dad to beckon to her every want and need after he's worked three nights in a row and hasn't had sleep since he last worked. Anyway last month she apparently quit her job and they didn't tell me until last night that my coverage ended April 30th. I have an ultrasound on Thursday! I have seen my baby since 7 weeks and I'm 20 now and I'm freaking out that I'm not going to get my ultrasound. My doctor doesn't do in office ultrasounds unless high risk she sends you to the hospital ultrasound tech and before you go in they check your insurance and everything. What I'm freaked out about is the that my husband and I just bought a new car on Wednesday and I decided to pay 6 months in advance for our insurance, so we don't have the money if I have to pay up front. Is there any suggestions on what I can do? I plan to go to the Medicaid office today to try for that insurance but I am worried they won't get it ready in time. Also, I know my dad is not required to have me on his insurance since I am married so please don't point that out, I'm not mad that they don't have me covered I just would have liked to know early enough to prepare for my baby. Thanks for any advice.