Well, as the more skinny, nerdy, guy, that everybody liked in school but never felt like hanging out outside of school, it just feels awkward, especially if I accidentally swiped and they did the same way. Just seeing their picture makes me feel weird.

If they did, they either wanna hangout or are into you or matched you ebcause they recognized you.

I always match people i know because it's funny talking to one another on tinder.

Second, i am also naturally introverted. I'd rather sit at home watch a movie with a few friends than go to the park and so on.

I do like company but not partying too much. On the other hand, i do party like crazy just because i wanna have the experienc and also talk to girls and get drunk with friends.

If it was up to me i'd rather do something else, but when everyone is going to a party, it's a shame if you don't go. ;)

3rd, Confidence is indeed what i am talking about, and as you highlighted, you're confident in a rather different spectrum that what we are talking about.

Give me a girl and i have no problem talking to her, give me a presentation and i have no problem doing it(been shaky a bit due to lack of practice) but put me infront of a professor or my future boss and i'll freak the fuck out.

It's because i've done some of the things many times, while the others not. It is not often the case that you are naturally confident in everything you do, and if it is then good for you!

Btw have you actually partied and gotten drunk with friends or do you assume you are not the type of guy for it without doing it?

I'm not saying you should do it. I'm just saying life is all about experiences.

Also for the gym part, just head over to /r/Fitness or /r/bodyweightfitness and follow the one of the recommended routines. As you are a beginner, you'll see substantial growth in a short period of time, that is a few months which might motivate you more.

Or you might figure out that fitness is not for you, which is completely fine too but there's only one way to find out. :)