Wa'alaikumsalam sis! I totally understand the worry, first pregnancy memang semua jadi besar dalam kepala kita kan A few of my mum friends also had smaller sacs at that stage, and their doctors said the same thing, it's within the normal range even kalau nampak kecik by standard charts, dating bisa jadi off by a week or two je, which makes a big difference at 6 weeks. The wait till week 8 memang torture, but that's actually the best time to see things more clearly, so try to breathe and not stress yourself too much (easier said than done, I know!). If your doc isn't worried, that's a good sign, trust that, but if your heart keeps racing with anxiety, boleh jugak call the clinic and just talk it through with them again, sometimes that helps calm the nerves more than talking to aunties sahaja. You're doing fine, mama!