5 weeks ultrasound

Hi guys. I have had my first ultrasound today. From my calculations i am currently 5 weeks and 4 days. This is based on the first day of my ovulation because my periods are irregular due to endocrinology issues. My ovulation was on the 30th of march i was testing negative prior. My first positive preg test was on the 10th of april. On todays scan they only saw the sac no yolk or baby, anyone had a similar issue. This is my first preganncy after ttc for 7 months and i have horrible anxiety.