[onion2k]

I feel like I'm being exploited

An important question to ask yourself is whether or not that would that change if you get paid a few thousand Euros more?

Chances are that it wouldn't. Really you're not looking for just a pay rise - you're looking for a promotion so you get recognition for what you're already doing. Talk to your boss about how you can make that happen.

[throwAwayFr]

Maybe its because I see people doing the same or less work as me, are getting paid (and therefore appreciated) more.

I don't know what a promotion or recognition would look like, or how i might ask for one?

[onion2k]

are getting paid (and therefore appreciated) more

I'd be willing to bet many of them feel exactly the same way you feel. They'll feel they're under-appreciated and unrecognised for what they do, and they'll think more money will change that. It won't. How much you're paid is not a sign of how well you're appreciated.

[throwAwayFr]

I get what you mean. But I honestly think I'd feel at least a bit better if i was financially doing better.