I can't believe that it's still the New Year's. It already feels like we're in the middle of January.
It feels like half of January is over.
ご質問ありがとうございます。
"I can't believe that it's still the New Year's."＝「まだお正月だとは信じられない。」
" It already feels like we're in the middle of January."＝「もう一月中旬のような感じがする。」
又は、
"It feels like half of January is over."＝「一月の半分は終わったような感じ。」
ご参考までに。
アメリカ合衆国 
