YOU SAID:

My niece is waiting outside and i broke my back yesterday so just give her the cat

INTO JAPANESE

私の姪は外で待っていて、昨日背中を折ったので、彼女に猫をあげて

BACK INTO ENGLISH

My niece was waiting outside and broke her back yesterday so give her a cat

INTO JAPANESE

私の姪は外で待っていて昨日彼女を骨折したので彼女に猫をあげました

BACK INTO ENGLISH

My niece was waiting outside and broke her yesterday so I gave her a cat

INTO JAPANESE

私の姪は外で待っていて、昨日彼女を壊したので、私は彼女に猫をあげました

BACK INTO ENGLISH

My niece was waiting outside and broke her yesterday so I gave her a cat