I'm 18 weeks pregnant, and my work shirts just make me look fat...?

I have to wear a uniform polo shirt for work. I lost some weight so my work shirts were a little too big to begin with, but now that I'm 18 weeks pregnant and my belly is starting to poke out, I just look fat and sloppy in my oversized work shirt. Getting new shirts and making permanent alterations aren't options. I'm wondering if it would look silly if I tied a ribbon or something around me to accentuate my baby belly, so it doesn't just look like I had a few too many twinkies, or if anyone has any other suggestions. Thanks!!