My work trousers don't fit now, I've had two weeks off and just tried them on several days ago. I'm 10 weeks now too.
I'll only be working until about 22 weeks (not my choice, made redundant), so I begrudge buying expensive tailored maternity work trousers as I won't use them later on. I've settled on leggings with really long jumpers and tunic type tops, this seems to be acceptable work wear for pregnant women in my workplace, so I'll make those last out the next few months. After that, I'll be able to wear what I want as I won't be working, that'll be a lot easier.