I would try not to worry, if you have been to the doctors and they say everything seems fine, and you haven't had any symptoms worth worrying about then you should be okay. Hope you have a healthy rest of your pregnancy :)
There's nothing wrong with only drinking water. It's the best you can put into your body. It's when you don't eat it becomes a problem.
As long as you are taking folic acid and prenatals now, you should be fine.