Maybe mention at your scan that you're undecided with finding out the gender? Then see how you feel after you see his/her little face etc. Good luck!
This is what I would do, give your self steps and then follow them one by one, if after seeing the baby and you are still not sure. Ask them to write it down. That way you have a photo to look at a bit more and maybe by yourself when you can think more. Then if you still want to know you have it written down.
Just make sure if you do get in written down, put it on thick paper and fold it a few times so you can't see by holding it up to the light

Good luck tomorrow and don't put to much pressure on yourself to bond or you might stop it from naturally happening.