Is Tameka really pregnant?

I am still reading so much info on the cancelled wedding that was to be this weekend for Usher and Tameka. Some sources are saying it was called off for her criminal record, some are saying that she may have lied about being pregnant, some are saying that Ush just came to his senses. But I do have a question. They claim she is pregnant and due in December. That's the 12th month. A baby takes 9 months. That makes the time of conception around the 3rd month, March and therefore she should be about 4-5 months along. Why is she not showing yet? If she was that far along, she would be showing big time...that is...if she's pregnant. I'm sure there will be more to come.