I don't drink too many fluids..

I work from 4:30 PM or 5 PM to 2 - 3 AM. When I wake up around 10 to 11 AM. I start drinking throughout my day before going to work around 6 - 7 cups of water. I obviously drink water with my meals or if there's any watermelon or pineapple I blend them and make a juice out of them. While going to to work I only drink about 2-3 cups of water. I feel bad because I'm 12 weeks and a few days along. My manager tells me customer service comes first if not they'll be such assholes to you. Once we close I start drinking about 2 - 3 cups of water before I get home. Is this bad ?
Btw I am a waitress and I can't leave my tables unattended since we are very popular restaurant.