Hi, I Have A Question About Yolk Sac, My Last

Hi, I have a question about yolk sac, my last ultrasound says that my yolk sac is enlarged with a size of 8.2mm, after 10 days now its 4mm which is the normal size, is this a good sign? Also, is this the cause why fetal pole is having a slow growth due to lack of nutrients, fetal pole from 2mm now at 4mm with the 10 days difference, diagnosed at 5+6 and now at 6+6 gestational age of sac. mean sac diameter of 19mm, no Heart beat.