Aw mama, I totally get the worry, first time mom kasi talaga ang feelings ay everywhere! A few of us in my circle had similar situations with measurements being off by a few weeks, and honestly, sometimes it's just genetic (like if both parents are petite) or the baby's own growth pattern, hindi automatic na may problema. One of my friends' baby was also measuring behind sa haba, but normal naman lahat ng iba like your baby, and she came out perfectly fine, doctors said it was just how that particular baby was meant to grow. But since this is something your OB wants to monitor closely with a follow-up next month, I'd definitely check in with her if you have any new concerns before then, because she knows your full picture best. In the meantime, make sure you're eating well and staying hydrated, sometimes that helps too! Sending you hugs, mamsh, ang damdamin mo ay valid pero you're doing everything right.