I actually wanted to wear makeup, but my skin is so sensitive so I ended up not wearing makeup often.

(I was a little confused. I think your intention is:

"I actually want to wear makeup more, but my skin very sensitive, so I don't wear makeup often.")

And I wasn't going to wear makeup to work, but since my boss told me to wear makeup, so I have started to wear makeup to work.

I used to only apply the only sunscreen. But one day, a friend said that I should try a new BB cream from B company.

So I did and I thought it fitted me well.

<em>(It fit me well = </em><em>마음에</em><em> </em><em>들어요</em><em>?

Saying "it fit/suits me well" only works with certain things. I think you should say "and I liked how it looked on me" here)</em>

So now I've started wearing makeup much more often.

<em>Comment: Nice!! Your writing is awesome. Keep improving :)</em>

I got some pimples on my face so I visited the dermatologist.

(Sounds good maybe try "I had" instead of "I got" to sound more natural)

(But) The only thing they did was pop some of them and then gave me a prescription.

it took roughly 10 mins.

("Which took roughly 10 minutes" would make it sound more natural and fluid between with the previous sentence)

When I went to the counter to pay for everything, they said the total cost was 40,000won…….omg.

I guess money seems to (just) vanish into thin air…...

(Very good)

My overall comments: you're already a very good English writer compared to most Korean people. Keep practicing and you'll become a professional in no time!