Measuring Behind- thoughts?

Kristen

Went for my first US, should be 8w4d according to LMP. Actually only measuring just at 6w, baby was there but no heartbeat detected (which they said was normal for that size). I’m pretty confident on my days but only had a couple months of periods before coming off the pill so it’s possible I guess. Now I have to wait 11 days for my next US 😢🙏

Anyone experienced something similar??