Seven week ultrasound

I go for my first ultrasound tomorrow, and I should be at seven weeks tomorrow. Originally it was supposed to be next Monday but they called me and asked if I had one scheduled with them and I told them yeah and when it was for. She asked if I wanted to move it up to tomorrow or Wednesday so I told her tomorrow because I have work Wednesday. I’m really scared something might be wrong. Like I just have a bad feeling. I was in the hospital over night and realized Friday due to not being able to eat and throwing up, my potassium levels where low, and I was dehydrated. My vitals at nine something or so that night was about 130/ 60 something, about two to three hours later it was 88/53. I’m just really worried. Also my ultrasound is scheduled at pregnancy center, they have no idea I was in the hospital. I just personally feel like it’s a bad sign