UPDATE: I went in for my interview a few days ago at the temp agency and it went so, so well! I've always been really good at job interviews, and was really happy to continue my streak.
I did end up telling her I was pregnant for a few reasons: A. I wanted to explain why I didn't want a full-time job and preferred to stay as a temp, B. I had to ask if it was okay to be taking off time to go to my doctor and mid-wife appointments, etc, C. I suck a lying, I really really do and D. I look pregnant, including the sea-bands I won't take off!
I suppose since she never knew me before she might not know I'm preggers by looking at me, but everyone else I know can! I'm going to be a fatty fatty two by four. ANYWAY.... the intervew went brilliantly, she's already called me about a job (that I had to turn down because of it's location) - but she's really keen on finding work for me.
Also - she said that even though I'm preggers and only want to work for the next 5 or 6 months, that I'd be a long-term employee of theirs by then, as most people are only there a brief time before they get hired on permanently or leave for school or whatever, so she was actually really happy to have me for so long.
Whee!