Transvi Ultrasound...Will it provide answer to...?

I highly doubt the doctor 'lied" about how far along your cousin is lol. Idk why your cousin would want to lie about that either. But just for the record yes, a transvaginal ultrasound will tell how far along she is based on the growth of the fetus. So all the "lies" will certainly be cleared up at that ultrasound! :)