YOU SAID:

I’m very tired and should be doing my homework

INTO JAPANESE

私は非常に疲れていると私の宿題をしているはずです

BACK INTO ENGLISH

I am very tired and should have done my homework

INTO JAPANESE

私は非常に疲れているし、私の宿題をすべきだった

BACK INTO ENGLISH

I am very tired and should have done my homework