i have 3 weeks to sort out an outfit online, arrive in uk and have about 8 hours turnaround for an outfit and undergarments. i need the definative stomach tamer. im 14/16 on top and 12 on the bottom but hopefully wearing a one shoulder or strapless dress. is it spanx?have 9 days to order then 11 days of no internet access so need to get sorted asap. tia.