Initially I started sewing at regular intervals but I ended giving up halfway because it was too tedious.
ご質問ありがとうございます。
この場面、「最初のうちは等間隔で縫っていたけど、[途中](https://eikaiwa.dmm.com/uknow/questions/34681/)から諦めた」は英語で言いたいなら、「Initially I started sewing at regular intervals but I ended giving up halfway because it was too tedious.」と言えます。
ご参考になれば幸いです。
At first I was sewing in evenly spaced interval, but halfway through I gave up.
"最初のうちは等間隔で縫っていたけど、途中から諦めた"
- At first I was sewing in evenly spaced interval, but halfway through I gave up.
最初のうちは縫い目を揃えて縫っていたけど、めんどくなって、途中から諦めました。
- In the beginning, I aligned the seams and sewed, but it became too much of a hassle and I gave up halfway through.
アメリカ合衆国 
