Measuring 5 Days Behind

I had my first ultrasound at my obgyn last week at LMP of 7+3. I had an external ultrasound. The tech said that the baby is measuring 5 days behind at 6+5, but said that can be normal and that it could come down to ovulating a few days later than expected or baby not measuring accurately because of earliness. She put my mind at ease during the ultrasound, saying everything looks as routine as could be, but now I’ve sat at home this week stressing a little.

My next appointment if my 12 week appointment (still 5 weeks away) and that appointment is specifically a pelvic exam. I’m concerned there will be no way to confirm at that appointment whether the baby is still there and growing successfully. Could I request to hear the heartbeat? That is the same week I was hoping to make an announcement, but fear to do so without confirmation everything is okay. I just don’t know what to expect.

Can anybody out there possibly calm my nerves? Im just fearful and want to have faith that my baby is growing and still there/healthy.