YOU SAID:

I eat oranges every Sunday since I was fifteen

INTO JAPANESE

私は15歳の時から毎週日曜日にオレンジを食べています

BACK INTO ENGLISH

I've been eating oranges every Sunday since I was 15.

INTO JAPANESE

15歳の頃から毎週日曜日にオレンジを食べています。

BACK INTO ENGLISH

I've been eating oranges every Sunday since I was 15.