No heartbeat yet.. :(

Based on my tracker, I am supposed to be at my 9weeks3days today. I just did a Transvaginal Ultrasound and my doc couldn't find a heartbeat and the measurement of my gestational sac is only at 6weeks. I am freaking out now but doc is asking me to come back 2 weeks later for another ultrasound to determine.... The wait is killing me. Did anyone encountered the same issue before? #advicepls #1stimemom