I was a little nervous because it was my first lesson, but you were really nice so that helped me to enjoy our conversation.
I was a bit unsettled during our first lesson together, but you put me at ease and helped me to enjoy the lesson by being so nice.
この場合、次のように言うと良いでしょう。
ーI was a little nervous because it was my first lesson, but you were really nice so that helped me to enjoy our conversation.
「初めてのレッスンだったので、ちょっと緊張しましたが、先生がとても優しかったので会話を楽しめました」
ーI was a bit unsettled during our first lesson together, but you put me at ease and helped me to enjoy the lesson by being so nice.
「初めてのレッスンの間、ちょっと緊張しましたが、優しくしてくれたので、安心してレッスンを楽しめました」
緊張していることは nervous の他にも unsettled を使って表現できますので、覚えておくと良いでしょう。
ご参考まで！
I was nervous, but because of the friendly environment, I was able to be myself and speak.
Even though I was nervous at first, I was able to be myself and speak freely because of the friendly environment.
ご質問ありがとうございます。
「緊張したけど、優しい雰囲気のおかげで楽しくしゃべれた！」は英語で「I was nervous, but because of the friendly environment, I was able to be myself and speak.」と言えます。
また、「初めてなので最初はちょっと緊張したけど」と追加したいなら、そうすると、「Even though I was nervous at first, I was able to be myself and speak freely because of the friendly environment.」になります。
特に内容は変わりませんが、「Even though I was nervous at first 」と追加したら、言葉の順番に影響がありました。
ご参考になれば幸いです。
I was nervous but I was able to have fun and speak thanks to the friendly atmosphere!
"緊張したけど、優しい雰囲気のおかげで楽しくしゃべれた！"
- I was nervous but I was able to have fun and speak thanks to the friendly atmosphere!
「初めてなので最初はちょっと緊張したけど、先生の優しい雰囲気のおかげで、楽しくしゃべれました！」
- This is my first time so I'm a little nervous, but you [先生に向けて話している、先生のおかげで] were so friendly and made it easy for me to have fun while talking!
カナダ 
アメリカ合衆国 
