職場で、通常４人居るはずが昨日は自分ともう一人だけ「んーもう、昨日は二人しか居なくて大変だったよ！」=I had a hard time because there were only me and another person there yesterday, why didn't you come here? Sorry I promise no to do that again.で可？
A: I had a hard time because only me and another person were there yesterday. Why didn't you come?
B: Sorry! I promise not to do it again.
あなたがやってみた文は書いたままで大丈夫ですけど、人と話しているとき、以下の会話は良いと思います。
A: For goodnessake! It was really tough yesterday with just two people. Where the heck were you?
B: My bad, man. I won't do it again, I swear.
んーもう = for goodnessake (怒っているとき、あまり無礼じゃない表現です)
heck は怒っているときに子供も使える言葉です。
my bad = 悪い (僕のせいだと認めるという意味です。)
swear = promise (両方を使えます)
There were only two people working yesterday, so it was an extra tough day for us.
この場合、次のような言い方ができますよ。
ーThere were only two people working yesterday, so it was an extra tough day for us.
「昨日は2人しか働いていなくて、私たちすごい大変だったんだよ」
it was an extra tough day で、いつもに増して大変な一日だったというニュアンスです。
ご参考まで！
アメリカ合衆国 
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