Due date question

Ok . so my LMP is July 30 . I'm supposed to be 37w2d now but based on my first utz I'm only 35w5d . I'm having my prenatal check ups on a public hospital the first ob that checked me said i should go by my LMP and the last time I asked (diff ob) she said my first utz . I'm really confused . anyone can help me?

Lmp due is May 6

Utz due is May 17

My 1st utz was made when I was 14w pregnant