While I don't want to parrot what so many have already said very clearly, I'll go ahead and add my two cents here.
First of all, I second, third, and fourth all those who said don't do too much while you're in the middle of exams. That's just asking for a mental breakdown. Moving on, when it comes to the subject of whether or not your art is up to par, I don't think it's fair to yourself to compare your work to others. It could be you're better than you suspect. Or that your art has something to offer that others don't. Visual art, at least in my opinion, is such a subjective medium. And while I won't argue that there's no such thing as a bad artist, I feel like comparing yourself to others is very unhealthy.
There's always going to be someone whose work is more successful than yours, more popular than yours, and viewed by the masses as just being objectively better. That's true for writing as much as it is for comics and drawing. But that doesn't mean you have nothing to offer. Far from it.
So relax. Finish your exams. Keep expanding your portfolio and honing your craft. And if you feel ready to share with the world, go for it! You'll never know unless you take that step. But don't get too hung up on whether you measure up or not. Because I guarantee that if you're passionate about your art, there will be someone out there who absolutely loves it. 