if she got a positive test on 19th jan, let’s assume at that point the earliest she could be is 4 weeks pregnant (14 days past ovulation), at a push 3 weeks pregnant (7 days past ovulation) but you would not be likely to get a positive test at that point, so if she was around 4 weeks pregnant on 19th jan you would expect that she would be around 7 weeks pregnant now - I think more should have been seen on a scan at 7 weeks, I’ve had a scan at 6+2 with my last pregnancy and seen the fetus and heartbeat
I’ll tell you about my experience with a missed miscarriage, got a positive pregnancy test on the day of my missed period, so was 4 weeks pregnant at that point, 6 weeks later when I was supposed to be 10 weeks pregnant I started spotting and getting cramps, went to EPU for a scan, only a pregnancy sac measuring about 6 weeks could be seen,no fetus, no heartbeat etc, they told me I had probably just got my dates wrong and might just be a lot earlier then I thought, so I went away with a bit of hope, until the sensible part of me thought about that positive pregnancy test I’d gotten 6 weeks earlier - there was no way I could be earlier then 10 weeks based on the date I got that positive test, I’d had a blighted ovum, I think there’s a good chance it’s a missed miscarriage for your friend to be honest, although I’m not an expert, maybe it’s normal for some women to only see a sac and a pole at 7+ weeks, hopefully it works out ok for her