Did she?she's acted like any other girl in her 20s.
After graduating, she didn't work at all for a couple of years until the press got so bad she got a 3/days a week job at Jigsaw. She told her employer she didn't want to work more because she wanted to have time for her boyfriend (the employer confirmed that in an interview) and she hanged on to that job for less than a year.
Considering she felt comfortable asking a stranger to give her a part-time job to accommodate her private life, I think people who believe that her work for her parent - whatever that was - was anything more than something to keep her semi-busy while she waited for William to call are exceedingly naive.
De La Renta is very matronly. Burberry is way too fashion forward for her level, she would look beyond awkward in their clothes.De La Renta, Burberry Prorsum, even Ralph Lauren
I do like the RL suggestion, but only for day-wear.