Well, off the top of my head, I'd say replace the top with a less baggy one, with a darker colour to match the rest of your outfit if you have one. And yeah, don't wear leggings if you don't think it'd look good - you want to feel comfortable with how you look so you can be chilled out and cool on your first date! If you're giving out lots of positive energy, that will make much more of an impression than what you're wearing. Have fun!
Hi you shouldn't feel as though you have to cover up with cardigans to hide what you called 'extra weight'. If you wear dresses, you should treat yourself to one that helps with contouring your body. This is what an actual 'bodycon' dress is. Take a look at this link for ideas of dresses that contour is a sophisticated way.
Hmm yeah the cardigans is kinda out of place. Anyway, wear the most comfortable dress you think. Date would be perfect if you are comfortable of what you are wearing.
I'd ditch the cardigan thing, its hideous!