I've resorted to online shopping, being now a 32 HH. It is absolutely impossible to get anything at a regular shop, and I don't want to pay $200 at a specialty shop. I've been buying lately at Breakout Bras - they carry some really nice regular, maternity, and nursing bras, in a WIDE range of sizes, at decent prices. ($40-90 or so). They are a North American company, and they ship free to North America, so I don't know what the shipping would be to Aus, but it might be worth a look anyways. They also give good directions on how to measure yourself, and find the right size, and they provide online help as well - e-mail them any questions.
Otherwise, I've heard that Figleaves is a good site....? UK, I think?

Hope you find something great soon! There are enough issues in pregnancy without having to worry about your boobs popping out, or flopping all over.