since you have completed your MS, it would make sense to retake PGRE. your profile is quite good though harvard etc probably expect more. Also you've done your MS from United States, that should definitely work in your favour if you choose your schools wisely. If your job is related to your field of ineterest i suggest you continue, if not, and you are very keen on pursuing PhD, take up a few more courses. BUT do not retake the pgre if you don't quit your job because in my opinion a score lower than 660 in ur second try could make things worse. On the other hand a good score will make all the difference.