The happiest moment of my life was when I successfully expressed my feelings to him. It was my first time doing so, so I was incredibly nervous. He said yes when I told him I'd like to go out with him. I was so overjoyed that I felt like jumping around.
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、
The happiest moment of my life was when I successfully expressed my feelings to him. It was my first time doing so, so I was incredibly nervous. He said yes when I told him I'd like to go out with him. I was so overjoyed that I felt like jumping around.
とすると、『私の人生で最も嬉しかったときは、彼に私の想いを上手に伝えられた時です。初めての[告白](https://eikaiwa.dmm.com/uknow/questions/13742/)だったのでとても緊張しましたが、私と付き合ってほしいと彼に言ったら、彼はいいよと言ってくれました。私は飛び上がりそうになるくらい嬉しかったです。』となります。
参考になれば幸いです。
日本 
