Aww... I know that feeling well when it comes to gender. I lost my first baby at 20 weeks. It was a son that we named Tyler. Just 4 months after his birth we were pregnant again. I just knew I was having a boy and I felt very attached to 'him'. At our 17 week ultrasound the tech said "I don't see any boy bits" and I almost broke down right there on the table. As we left the hospital that day my husband was beyond elated because he wanted a girl so bad but me, well, I felt as though I had lost my boy twice.
It took me a little while to come to terms with the idea of having a daughter. I had always imagined myself with all boys for some reason (probably because I had 2 brothers and mostly male cousins and always got along better with boys). By the time my daughter was born I was completely ready for HER and didn't feel upset in the least that she was a girl but it took some time and adjustment.
Fast forward to the next baby... I was so sure I was having another girl. We tried to find out the gender but baby was uncooperative laying butt up covering the important parts. The doctor wouldn't even venture a guess. My pregnancy felt just like it had with my girl and everyone around me said I was having a girl. My daughter was so sure the baby was a girl too and they say kids can usually sense it. When the baby was born they didn't even tell us what gender we had. I was waiting for that big "Its a ____!" moment but we didn't get it. The baby was laying in the warmer crying and I asked my husband what we had. He looked up at the doctor who said "Oh, its a boy" I cried. The anesthesiologist asked if I was crying because I was happy and I lied and told her yes. Truth was, I was devastated at the idea of having a boy this time around. I had pictured my two little girls playing with one another even. I was definitely mourning the little sister my daughter suddenly wouldn't have. It took me a while to get past the feelings this time too. The first few days I couldn't even call the baby by his name or refer to him as a boy. He was just a 'baby', nothing more. No gender. I wouldn't dress him in boy colors or even think about him as a boy until I changed his diaper. It took me a few days to adjust to the idea that he was a boy. It really made me wish I had been able to find out ahead of time the gender because I didn't bond with him the way I had my daughter.
I used to get so angry when people would comment "now you have one of each" or "a full set", etc. I hated it. Why did society think that I had to have a girl and a boy to be happy. Wouldn't I be just as happy with two girls or two boys? Ugh. It still bothers me when people comment that at least I have one of each. I adore my kids but I love them for who they are, not for their gender.