Wear the suit, Dettu.  You can always dress up with jewellery and scarves.  If you wish to wear your dress that can be dressed up with a jacket and accessories.  My killer-outfits in which I landed my current job were a black suit for the first interview and for the second interview a plain black dress and a scrumptious red jacket.  As long as you are immaculately turned out then you will look just fine and feel confident.