Even if my room feels like it's full of things, it's okay if they're things I like.
I like a room that's full of things I like even if it feels crowded.
この場合、次のような言い方ができますよ。
ーEven if my room feels like it's full of things, it's okay if they're things I like.
「私の部屋が物でいっぱいでも、それらが私の好きなものなら大丈夫」
things I like で「私が好きな物」
ーI like a room that's full of things I like even if it feels crowded.
「狭く感じても、好きな物でいっぱいの部屋が好きです」
a room that's full of things I like で「私が好きなものでいっぱいの部屋」
ご参考まで！
I personally prefer being in a room surrounded by things that I like, even if that means the room is smaller for it.
こんにちは。
ご質問ありがとうございます。
"I personally prefer being in a room surrounded by things that I like,"＝「個人的に、私は自分が好きなものに囲まれている部屋にいるのを好みます、」
"even if that means the room is smaller for it."＝「部屋がその分、小さくなるとしても。」
ご参考までに。
カナダ 
アメリカ合衆国 
