Thank you all so much for replies & inputs!

I feel relief already knowing it's common amongst pregnant women. As grub17 nicely put it, "oh the joys!"

I will hunt different brand of liners and try them until I find the one that's not irritating. I've been using the same brand for years and it's non-perfumed, so it didn't cross my mind this could be the problem but maybe being pregnant making me more sensitive this time.

I have been knickers-less in the past few weeks, as much as I could when I'm at home. So the liners probably the main problem. My 'pregnant undies' are bigger than what normally I use when not pregnant, so should be enough room there. Although I'm keen to try and see what wearing undies with a 'ball space' feels like! Sounds comfortable!