Spandex. Without a doubt, this is the very best anti-chafing barrier you can find.
I've been in the military for 10 years. When we're going to be marching for long periods of time, we wear spandex shorts under our combat uniforms. This is especially helpful in the heat.
If spandex is too tight or uncomfortable for you, my next recommendation is pantyhose or tights. They do, luckily, happen to make maternity hose, so you'll be able to get them when you get a bit bigger
Until your currently chafed skin is healed, I suggest that you Aveeno body wash in the shower (the sensitive skin variety has no perfume and is fantastically moisturizing), then dry by patting your skin gently, allow to air-dry, and use a corn-starch based powder prior to putting on your spandex or hose.
Also, don't forget to drink PLENTY of water! It's warm outsider and so very easy for a pregnant woman to dehydrate.
Be well!
C