History of 8 miscarriages, Lupus. Ultrasound shows increasing beta hCG level, increase in size of gestational sac, no embryo visible. Meaning ?

Hello there, I have just had an obstetric ultrasound by external in vaginal. As I have a retroverted uterus , the vaginal was more accurate. I am 40yo and my menstral cycle has not been regular at all. The result of my ultrasound indicates the following: Ultrasound examination confirms the presence of an intrauterine gestational sac . The sac is of 8 x 4 x 10mm (what do these measurements mean?) in size and is surrounded by a good decidual reaction. Thre is no extrachorionic haemorrhage. A foetal pole was not identified and comparison to the prevous images has shown a definite but limited increase in size of the gestational sac. (last scan was 9 days ago and measured 5mm). Conclusion: I note increasing beta hCG level and slight increase in the size of the gestational sac since the previous examination. However, an embryo is still not visible. A further progress examination is suggested in the context of clinical features. I have had 8 miscarriages and believe to have obstetric lupus . Can you please inform of what the above means.