Gender in Question

Ok I am a mother to two lovely boys one 15, the other 5, hubby got me on board for one last try for the girl but over 2 yes trying had nothin happen.  I can to terms and was moved past and bam prego! This pregnancy different than either boy and they were both similar and had hopes of a girl but first ultrasound at 15wk dr says boy, I won't lie I cried and have been working past some emotion but my OB does an ultrasound ever visit so the next I  closer to 20wks, then later same week saw a specialist as I am advice maternal age and they say boy.  Could these be wrong when the pic is so obvious as a boy?