MyTheresa.com's social media followers are in for a stylish treat this New York Fashion Week, as tastemaker and all-around cool girl Alexa Chung is taking over their Facebook, Twitter and Instagram feeds. The luxury online store has a history of pairings with strong women (and modern-day icons), and Alexa has joined forces with them before - starring in a profile as part of a series.With coverage from the front row, backstage access and a peek at the after parties, we're expecting to get serious lifestyle envy. Likely the only way to make ourselves feel better will be logging on to MyTheresa.com and buying ourselves a wardrobe to rival Alexa's… Celebrity posse not included.A-List Instagrams...