Job Interview...need some advice please!

Megan • Happily married. One 2015 angel baby, little girl born Sept 2016, & one due June 2019.
An amazing opportunity has presented itself to work for a better department within my company. I have to fly to the Charlotte, NC office next week for an interview (I'm outside of Philadelphia, PA) and I'll be 24 weeks pregnant that day. 
It's going to be warm in Charlotte, about 86° so I was thinking about wearing a dress. My company is "business casual" and most folks in the southern offices are casual. I want to dress a little nicer though. Do you think a nice dress like this would be ok with a sweater and heels? I'm open to suggestions. I'm so nervous too. They don't know I'm pregnant and I will need to tell them during the interview. No idea how to bring it up either.