We attempted to find out the gender of our second child, born just this January. After looking for about 40 minutes and wavering between girl and boy, the tech finally declared that she was "60-70/% sure" that we were having a girl.
Our second SON was born on January 27....lol
Sometimes, the baby just doesn't want to cooperate. Even if you don't have a follow up u/s scheduled (I didn't have another one until I was overdue and there was no way they'd be able to have told me the gender then because everything was so squished in there....and, besides, I was going to meet the baby at any moment by that point, anyway), just enjoy the surprise - I've been surprised twice now and don't regret it....you'll never experience anything like it :-)
Basically it means that no one knows the gender of your baby at this time. Do you have a repeat US scheduled?
At early ultrasounds it's extremely difficult to tell what they are. They're nothing more than a guess, and one you shouldn't take as a set answer. Around 19-20 weeks they're completely done forming and that is when the best guess is done. It's why some doctors don't tell you before then.