First off....CONGRATULATIONS!!!!!
Having 'baby dreams' and 'birth dreams' are common, and totally normal in women who are pregnant. The confusion about the sex of the baby suggests that you really have no preference, that you just want a healthy baby. But, because your husband called him by a boy's name, suggests you may be feeling that
he wants a boy...as well as the fact you may be thinking the baby IS a boy.
Your babies' genetic gender is decided at conception, but is only distinguishable after 6 weeks. As strange as it may seem....you already know which it'll be! That is to say,
your body already knows, because of the hormonal goings on within your body.
Depending on your body's build, you may already be 'showing'....and now you're possibly starting to refer to your tummy as him or her, rather than 'it' or 'the baby'.
Your dream is more than likely a result of your anxious waiting for the arrival of your new little human, and the feeling that it's time to start thinking about names.
Hope this gives you some insight.

Hugs, Hope & Happiness to You, Hubby & Baby!
J