Uy mama, I can feel your worry talaga! But honestly, with concerns about baby's size at this stage and your OB already mentioning CS as an option, kailangan mo talaga ng professional guidance, please follow up with your doctor on this one, ha, kasi they know your full picture best.
A few of us moms din nag-go through similar concerns, and it really varies from person to person, yung iba natulungan ng exercises and positioning, pero sa iyo kailangan ng proper assessment mula sa OB mo. What I'd suggest is ask your doctor directly what specific movements or activities are safe for your situation given baby's size and your measurements, don't rely lang sa general walking, okay?
You're not alone sa fear ng CS, mamsh, but sometimes it's the safest path for both you and baby. Talk openly with your OB about your worries, they can explain everything clearly and help you feel more ready, whatever happens. Sending you strength!