So nervous.

I am finally pregnant with my rainbow baby! My first pregnancy ended in miscarriage after my 7 week vaginal ultrasound. I was measuring about 5 weeks but there was no fetal pole. Right after my ultrasound I began bleeding and lost my baby. I have my first ultra sound next monday I will be 7 weeks 4 days and I am scared to death. Plus my lower back has been killing me. Any advice or support would be appreciated.