Early Ultrasound

I had a chemical miscarriage on September 2nd and found out December 1st I’m pregnant again with my rainbow baby! I’m so excited this will be my first baby. I am so anxious and scared that this time will end like the first did. I was supposed to be almost 8 weeks when I bled last time and was told the baby stopped developing around 5 weeks. So my question is how early can I go to get a vaginal ultrasound to hear a heart beat.... I’ve heard 6 weeks & I’ve heard 8. I don’t want to go too soon but really really want to hear the heartbeat as soon as I can to put my self at ease.