There are plenty of people on this forum that are more qualified than I am to give you advice, but I think I can give you some words of encouragement.
You have a solid GPA from a good school and a stellar GMAT score. Even as a mediocre analyst, you should be capable of finding a spot at more than one of the top 15 schools. I would imagine that the best way to stand out within the banker applicant pool is to demonstrate above average career progression or special assignments. Non-finance extra-curriculars will obviously help too, but I'm not the right person to suggest EC activities (I don't have many of my own).
Enjoy the banking job and learn as much as you can. Don't forget to have fun
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