Help girls/guys! Opinions on this outfit pretty please!

Hey everyone!!! Good morning/evening! I have a 'family reunion' type thing coming up next month, my cousin is getting married and family from England are flying over here to Australia, the last time they saw me I wore a dress that was australia size 18! This time it won't be! I won't be at the airport when they arrive but the next day we are all going out for a rehearsal dinner for the wedding! Sooooo this is the dress I brought 3 months ago, couldn't even get it past my hips to try on! It fits now (yay!) but do you guys think it looks ok to wear? It's a navy blue and I'll wear my hair up with some heels, what's your opinions?? Can I pull it off I'm worried I'm still a little bit the wrong shape for it and I rly don't want to look like the bigger girl in a tight dress lol thanks guys xox