First ultrasound

OK ladies I had went to the doctor because period like cramps and hurting in my back. So they told me to come in. So by my period I was 6w4d. So he comes in the room and starts the ultrasound he ask how often do I have periods I told him between 29-31 days. He said that explains it he said because of that I ovulate late and I was only around 5 weeks. He said I do see the pregnancy and it's were it's supposed to be and he see the yolk sac. He said which is a great sign but I am still worried. He had me to do blood work and for me have my blood work done again on Monday. Then I will have another ultrasound in two weeks. Has anyone had this happened and had a good out come?