Cattie, my DS was the same age when this all started for us. Our nappy covers have a fine liner of some sort of synthetic, and I think that the liner distributed the wee all over as soon as it started to soak through the insert, which is why the redness was all over. Changing him more often helped a bit, too - he was definitely worse if we only changed him once in a sleep-play-feed cycle, and was better is we changed him before and after every sleep.

Re microfleece vs polar fleece, I think they are similar but not the same. I use the microfleece I bought from an online nappy fabric supplier, and I've read that polar fleece from your local Spotlight isn't the same thing, or doesn't work the same way, or something, but I'm not sure.