I'm at 35 weeks..So, I've been wearing my birkies becos I could not fit into any of my flats anymore..... Luckily my workplace does not require me to wear formally..
I've seen many mummies wearing "Fit Flops" too... I tink you can buy them at Isetan... It is a sandals too.
Try to wear shoes that are not slippery.... I'm not sure if you will like Crocs....
Hope it helps.