Travel

I hadn't realized that I like travelling until I entered university, (and/ but) after a couple of trips abroad with my friends, I found exploring the planet awesome. The first two trips I took still remain beautiful memories. Back then I wasn't as mature as I am now, I was even awkward and clumsy at everything, and so were my friends Back then my friends and I were not as mature as we are now; we were awkward and clumsy at everything. Ironically, that is what made those trips amazing. We did some crazy stuff together because no one knew us outside of Korea and we weren't mature enough to know better. no one knew us outside Korea. We wouldn't have done that stuff if we had grown up. Even though I have gone abroad a lot many times after that, I still cherish those first two trips. the moment of my first and second trip. There are still many wonderful places in the world I'm planning to visit someday. Maybe I should make a fortune to keep so I can continue on my journey.

Notes:

1. (and/ but): both of these are fine, but they change the nuance of the sentence slightly. 

And: (Don't like travelling, go to college, start to like travelling, go on trips, find exploring awesome)

But: (Don't like travelling, go to college, go on trips, find exploring awesome)

So, "but" means the trips is what made you discover you liked travelling. "And" means you took the trips after you had already discovered you like travelling. 

2. "I found exploring the planet awesome".  This is an example of a sentence that just sounds awkward.  We would say, "started finding/ realized + "is awesome"/ discovered + "is awesome"".  There is not really a reason that I know of.

3. Back then my friends and I were not as mature as we are now; we were awkward and clumsy at everything.  

4. If you say, "Ironically, that is what made those trips amazing", then your next sentence needs to espouse on it.  Instead, your next sentence talks about how you did "crazy things" not because you weren't mature, but because people didn't know you.  This makes it sound awkward. You can add the part about "people not knowing you" but you can't have it being the only point.