Worried

I'm 7 weeks 4 days with twins. We had an ultrasound done at 6 weeks 3 days and both babies looks super strong and healthy with heartbeats of 121 and 114! I have an ultrasound tomorrow morning and I am scared to death that I won't have a good outcome..(I had a loss in February and got pregnant with my twins directly after)..I'm not spotting or anything just a bit of cramping and back pain..so I really don't have a reason to suspect something is wrong I'm just over thinking I think AND I'm super sick so I haven't been eating much even water is making me sick...advice?