Hey mama, at 27 weeks ka na kaya importante talaga makakuha ng ultrasound para makita ang development ng baby at placenta, hindi dapat ma-delay yan, kaya go lang and book na agad pag available, okay? I'd really suggest checking with your OB kung bakit delayed ang ultrasound mo, baka may specific reason sila or pwedeng i-reschedule sa mas mabilis na clinic, lalo na yung 2nd trimester ultrasound important for baby's health monitoring. One of my mum friends nag-late din ng schedule niya and the doctor explained it clearly kung safe pa rin, so trust your OB on this one! Praying everything's normal sa baby mo.