Help with dog :(

I'm 26 weeks pregnant and I've had my German Shepherd for about two years. She's almost 100 pounds now and is a good dog overall. But I messed up and never taught her not to jump, because she's never had to be around kids or anything. It seems to be too late to teach her. It doesn't happen all the time but every once in a while she will jump and hit my stomach. It happened twice today. She doesn't mean to so I feel bad getting mad, and my fiance gets mad too. Someone please help!! I can't get rid of her. I just don't know how to teach her. :( it makes me so sad.