Gender reveal was weird

So I had my ultrasound for the gender and I specifically told the ultrasound lady that I don't wanna know now but I want her to print the picture out and put it in the envelope like they usually do, ok she did the ultrasound and gave me a taped envelop. I took it to the bakery store for a gender reveal cake. When I went to pick up the , the baker told me that there was no picture in the envelope and that it was just a hand written note inside the envelop I gave her . I was shocked. So I took my cake and have my whole family there and we cut the cake and it was blue for boy. No one believes it, everybody is in doubt probably because I have a boy already and everybody was waiting for a girl. Should I request another ultrasound? Could there be a mistake from the hand written note?