Doctor has me worried...... please any advice would be appreciated

Amber
OK so I found out I was pregnant back at the end of may... I ended up going to the ER for minor bleeding they did an ultrasound an there was 6 week gestational sac.... I had my first appt today I am 10 week 4 days everything seemed to be fine until he could not find the heart beat.... the he pushed on my pelvic area an decided to send me for an ultrasound due to I'm not measuring correctly....... I'm measuring at 8 weeks when I should be almost 11..... I'm so nervous.... but I also think he might have been off alil because he is very old like retirement is in December when he will be 70..... any advice would be awesome I'm so nervous has this happened to anyone ?