Ultrasound

Hey guys, I was having some pain yesterday and I had some orange looking discharge after sex but then it stopped and havent had anymore. I went to the drs today to make sure all is well and because of the pain I was having on my right side. Well they did ultrasound and it showed gestational sac at 5 weeks and 2 days and then the yolk sac at 5 weeks and 6 days and she said she thought she might had seen the start of fetal pole but wasent sure yet. But no heartbeat. My question is is it to early to see heartbeat and fetalpole. I ovulated on Dec 5th or 6th which would put me at 6 weeks 1 day or 6 weeks and 2 days. My hcg on Dec 21st was 356 Dec 23 it was 773 and then dec 28th it was 3844 So im a little confused what's going on. I didnt start getting positive on my test till 16th. Im scared maybe I'm miscarrying. The tech said its probably just cause I'm early. But why would my dates not be adding up. I go back for ultrasound again on Jan 14. Im so stressed and sad. I just lost my son oct 14.