Ladies I need your help....

Monday April 6th I went to the dr for pregnancy conformation. My levels were 15,841. Perfect measuring right where I should be for 6 weeks. They did a bedside ultrasound which showed a yolk sac but no heart beat yet. They brought me back in this morning April 8th for another blood test... I just got a call saying my levels didn’t double that they only went up to 25,481. They want me to come in the beginning of next week for another ultrasound. Has anyone had this happened and everything turned out ok? Just need a peace of mind.