Should be 7 weeks 6 but fetal pole small

Jan • Mummy to my 😇Angel Findley born sleeping at 39 weeks 💙.. And 😇 angel Robyn late miscarriage at 16 weeks. 🌈 Lewis 02/09/2020 👼 👼👼ruptured ectopic and two miscarriage

First am high risk pregnancy due to ectopic in 2021, and i need blood thinners so i had a scan at 5 weeks 6 and saw a sac measuring 5 weeks 6, went back this week should be 7 weeks 6, there was a beautiful sac and yoke sac and a fetal pole with HB, but Fetal pole only measuring 4 mm should be 8-10 😩😥.. anyone had this and turned out ok?