Had An IVF. Due For A Scan. Different Sized Sacs Mean?

Hi, i m after an IVF here is the timeline of what happened and when : 21 January - egg retrieval (ovulation) 26 January - Embryo transfer with 2 hatching blasts 1 February - HCG 359 5th february - HCG 1790 13th February first ultrasound - showing two gestational sacs @ 9mm and 6.4 mm. No yolk sac no fetal pole visible. This was done by a vaginal ultrasound . I m freaking out and can t stop worrying. Last year, i miscarried at 8weeks with blighted ovum and things were very much the same as this time except my HCG levels were very low. I m due for another scan in 10 days. 1.Do you think there s any chance this can turn out into a viable pregnancy? 2. if it turns out this is a viable pregnancy, should i worry about the different size of sacs? is that normal? Dear Doctor, i don t want to see a reply which would put artificially my mind at ease. I want medical facts and your true opinion on this situation. thank you