An embryonic pregnancy

I wonder what the likelihood is that I was just too early in this ultrasound. According to my last period, I would be 6w2d. The gestational sac measurement would be around 6w4d. My HCG level last Friday was 1500 and progesterone was where they expected it to be. They SHOULD be able to see something... so I go again next week for viability ultrasound. Has anyone had this happen and it was just a little too early? She said it doesn’t look good, but I MAY just be too early. I’ve had 4 miscarriages and one other molar pregnancy. I also have. One 5 year old (first and only pregnancy that has finished)...