How to decide?

My scan is next Tuesday and i don't know if i wanna find out the sex or not. I'm really torn up about it actually. I really want another girl and would like to know if it is a boy before the birth. But i also think it'd be way cool to have that huge surprise at the very end and give me something to strive for, if you know what i mean? Sometimes i think, just accept what you're given and be happy about it. But i really do want another girl and i won't deny that. But it makes me feel bad. Also Jacob doesn't want to know. He won't be with me in the scan and he said he doesn't mind if i find out or not. I can easily keep the secret too. I just don't know! How do i decide this? What if i regret my descion one way or the other?