I'm going through the same thing! And I'm gonna find out @ the scan. I just told hubby it's my body. I can find out and keep the secret lol
One suggestion that might appease you both would for you to find out but keep it a secret for every one else, including your bf...you can still have the reveal party even if you already know. Maybe a little reminding him that as a pregnant woman, it is your prerogative to change your mind as many times as needed. :)