Aww, I totally get your worry kasi nakita mo na ang measurements na hindi tumugma, pero honestly this happened to me din sa first pregnancy ko and it turned out fine! Based on your LMP, you should be 9 weeks, pero ang dating ng ultrasound ay showing 6 weeks 5 days, that's about 2-3 weeks difference, which can happen dahil sometimes ang ovulation natin ay delayed or conception happened later than expected. I know it's scary waiting, pero I really think you should follow up with your OB agad para magmonitor, hindi ito something to just ignore, kailangan ng professional reassurance at maybe another ultrasound after a week or two para makita kung tumutubo pa ng normal ang baby. Sending you hugs, hoping everything is okay talaga!