I'm so worried 😫

I'm so worried. I only eat my 3 meals a day... I was so sick my first try.. Now I'm not but still don't eat a ton. I'm 19 weeks on Saturday... I barley drink water.. I drink a flavored water in the morning then sweet tea and juice throughout the day. My doctor said I should be big bc my torso is small.. I wasn't skinny when I got pregnant but I'm stomach hasn't gotten very big. I just feel bloated.. Not pregnant. When I sit and lay down I don't even look like I have a pregnant belly... I'm so worried tomorrow the doctors will tell us at the ultrasound that she isn't measuring up to date... 😓😓😓