gala dress?

Sorry, I really hate to do this..... but I don't have anyone else I can ask. My mom is no help because she is sweet and says everything looks good, and my husband picked a differnt dress because it was black and he can coordinate better with it, but I'm just not 100% on anything at this point. I'm super self conscious right now being almost 36w and gained 50lbs! (That's with going to the gym and watching my diet!) my husband got tickets to this great gala on Saturday and I think it would be so nice to go out on one last date night (not that we ever get any with our 4 year old) before our June baby gets here. Invites say cocktail attire (I'm an artist and hardly ever dress up.....if I do it's black) so I'm not sure if these are good options. It's just last minute and I'm having to find something to fit this shap and be decent. Obviously I'd do my hair and make up ;) I hope it's ok to ask yalls opinions here, I'm just so lost :/