YOU SAID:

i was sitting there eating a sand-which when she walked up to me

INTO JAPANESE

私はそこに座って砂を食べていた - 彼女は私に歩み寄ったとき

BACK INTO ENGLISH

I was sitting there eating sand - when she walked up to me

INTO JAPANESE

私はそこに座って砂を食べていました - 彼女が私に歩み寄ったとき

BACK INTO ENGLISH

I was sitting there eating sand – when she walked up to me

INTO JAPANESE

私はそこに座って砂を食べていた - 彼女が私に歩み寄ったとき

BACK INTO ENGLISH

I was sitting there eating sand - when she walked up to me

INTO JAPANESE

私はそこに座って砂を食べていました - 彼女が私に歩み寄ったとき

BACK INTO ENGLISH

I was sitting there eating sand – when she walked up to me

INTO JAPANESE

私はそこに座って砂を食べていた - 彼女が私に歩み寄ったとき