I can understand your disappointment in not having a girl. I knew I would feel the same if I only had boys before I had kids, but I ended up with two girls and now we are having a boy. I am a little freaked out about it.
My only advice is to not be too hard on yourself for how you feel. Pregnancy is a difficult enough time. Try to take good care of you, and remember what a wonderful mother you are to your son. Maybe if you think about how much you love him, and what a wonderful gift you are giving to him (a brother and lifelong best friend) you will feel a little better.
Good luck Mama
My only advice is to not be too hard on yourself for how you feel. Pregnancy is a difficult enough time. Try to take good care of you, and remember what a wonderful mother you are to your son. Maybe if you think about how much you love him, and what a wonderful gift you are giving to him (a brother and lifelong best friend) you will feel a little better.
Good luck Mama