I thought I could get by with my English skills when communicating with foreign colleagues.
こんにちは!
ご質問ありがとうございます。
ご質問について、いくつか言い方が考えられますが、例えば、
Back then, I used to think I could get by with my English skills when communicating with foreign colleagues. I relied on what I had learned for exams. However, when it came to actual presentations and similar situations, I found myself struggling. I didn't feel motivated to study further, so I ended up avoiding it.
とすると、ご質問にある内容を伝えられます。
役に立ちそうな単語とフレーズ
get by with ~で何とかやっていく
参考になれば幸いです。