Misdiagnosed?!?

Out of all my years, I have had 5 transvaginal ultrasounds, due to issues with my period and pain. All have came back normal and never mentioned any abnormality? I have one yesterday for my first prenatal visit and all of a sudden they mention a septate uterus???? How does this go unnoticed for 5 separate ultrasounds!?!?!? I’m so disgusted and heartbroken 😭😭😭😭