Second guessing..

In second guessing our decision not to find out the gender of our second baby. We have a 14 month old son and decided before we even got pregnant we weren't gonna find out with the second one. But today when I was in Target just browsing I have the overwhelming feeling that I needed to find out the gender. We really want a girl, and I have my hopes up it's a girl. But since that's what I want I know that won't happen. And I feel like I'm going to be disappointed when the time comes because this whole time I'm thinking it's a girl. And I know it's horrible to feel disappointed if it's not a girl, but I can't help it. Should we just find out what it is so we can prepare? Or still keep it a surprise?