Gender issues

I am 36 weeks and 3 days. At 19 weeks we had our one and only ultrasound and we're told it's a boy. We (and both our families) were totally surprised as everyone's guess was Girl. In the months since, I've found it really difficult to accept the fact that it's a boy. I have birth dreams all the time that the baby's a girl, and refer to the baby as "she" in my head. I honestly had NO preference gender-wise, it just feels so much like my daughter in there. I obviously am riddled with guilt because this pregnancy has been so breezy and the baby is healthy! 
I'm just wondering if anyone else has had difficulty coming to terms with the gender of their baby. I don't feel like I can talk to anyone about it because it seems petty and selfish to focus on it. It's just that every fiber of my being thinks it's a girl--I haven't even been able to really think about baby boy names! 
Sorry so long-winded, it feels good to finally put these thoughts to words.