Making a contraction of a name starting with Maria is a time-honored tradition: Maria Teresa becomes Maite, or Maria Soledad is known as Marisol. So your nickname idea makes a lot of sense.

It's also smart to have some cross-cultural sensitivity about names. If you had invented the name Aditya for yourself, I'd caution that it is a familiar, and hugely popular, name among Indian men and boys.

But Malendra actually isn't. Globally speaking, it's an extremely rare name, one that very few people will have heard of. You’re right that it is occasionally used for men in India, but in this case, Internet searching has led you a bit astray. It's easy for these searches to distort our perspective. You can get thousands of Google results for practically any attractive string of letters. But if you drill down, they often amount to very little in terms of baby-name impact.

I think you should go ahead with Malendra as your nickname. If you need some help encouraging your friends and classmates to use it, this advice for stopping a nickname certainly works in your situation too.