Congratulations on your degree - it sounds like a tough course!

The firms are looking for people who excel in what they do - both in academics and in what they do outside of academics. It sounds like you have the components to be able to do this - but you will need to build out a coherent story. 

First, you need a killer resume which clearly lays out, with statistics, what you’ve done which is extraordinary. Things like:

• You're graduating top of your class (don't include the bit on the top 30% of the school - they want people in the top 5%). Is there anything else that you can add in which will demonstrate academic capability? e.g., have you sat any other standardized tests (GMAT, GRE etc). If so and you’ve done well (top 5th percentile) then add this in
• You've worked while you were studying - in what sound like some highly academic fields. How have you demonstrated the qualities that they’re looking for in your course? Things like leadership, entrepreneurialism, analytic capabilities. What have you done which demonstrates that you've gone above and beyond?
• What else have you done outside of your studies? Have you led a club? Started a club or endeavour of some sort?

It’s worth going to the open events that the firms host and get to know the recruiting team. Be curious when you go - it drove me mad as a recruiter when people came up just to try to get me to know them but weren’t curious about the company. Go armed with a list of things that you want to know about - and find out the answers! You can explain your situation to the recruiting team and they’ll remember you when they see the application.

Good luck! And let me know if I can help more at all.