Maybe it's actually trendy at the moment, and I'm the only one who doesn't know about it!
I might be the only who doesn't have a clue, but ○○ might actually be popular!
ご質問ありがとうございます。
① "Maybe it's actually trendy at the moment,"＝「もしかしてそれは今はやっているのかも」
"and I'm the only one who doesn't know about it!"＝「そして私だけがそのことについて知らないのかも！」
② "I might be the only who doesn't have a clue,"＝「私だけが全然知らないのかもしれない」
"but ○○ might actually be popular!"=「でも○○は実は人気なのかも！」
ご参考までに。
I might not know about it, but it could be quite popular.
I might not be aware of it, but actually it could be the in thing.
この場合、次のような言い方ができますよ。
ーI might not know about it, but it could be quite popular.
「私が知らないだけで、すごく人気なのかも」
popular で「人気のある」
ーI might not be aware of it, but actually it could be the in thing.
「私が知らないだけで、本当は流行ってるのかも」
in thing で「流行のもの」
ご参考まで！
アメリカ合衆国 
カナダ 
