Worried

So I had some lower back pain yesterday and I went in to see the doctor. He did a exam and an ultrasound. I'm 6 weeks today. They saw a gestational sac but no fetal pole. He said it could be too early to tell because it's so early in the pregnancy that's why they don't do ultrasounds til 8 weeks. He also noticed a corpus luteum cyst on my left ovary which he said is normal in pregnancy. I got blood work today and for Monday to make sure my levels are rising. I've never had a mc. This is my third pregnancy. Did anyone else have this issue?