jumping into this a bit late, and so summarizing what others have said, but offering my own 2 jiao none the less...
wanting a girl or a boy doesn't make you a bad person. Wanting one or the other to the point of rejecting a child at birth would, but that doesn't seem to be your problem. Anyone who says
as long as baby is healthy
has their instincts in the right place.
My wife and I were offerredd the opportunity to learn our child's sex before she was born, but I demurred at the contribution. Like TLD, we waited and found out, and yes the surprise was really cool. Worth waiting for, maybe worth more because waited for. As it was for my 2 kids from my first marriage, as no doubt it would be if (heaven forbid!) we decided to have more kids. Becoming a parent is a special moment in anyone's life, and that special moment of shared accomplishment and responsibility doesn't need to be tainted with "I didn't get the colour I asked for" selfishness.