The tense of the reported speech changes depending on the tense of the main verb in the sentence.
Amy (has) told me that if I can..., I will be able to... .
Amy (had) told me that if I could...., I would be able to... .
You would use the first if the possibility was still open; i.e. you hadn't made yet it before 6 o'clock but you still had time to do so!
You would use the second if the possibility is further in the past and now closed i.e. it is after 6 o'clock - it doesn't matter if you did or didn't make it in time!
Student or Learner