Should I use past perfect in this sentence?

Question

Should I use past perfect in this sentence? I've come up with three options:

1. I forgot to add them on Sunday, so I added them today.
2. I've forgotten to add them on Sunday, so I added them today.
3. I forgot to add them on Sunday, so I've added them today.

Which one is correct? If it isn't any of them, how can I articulate this sentence in a grammatically correct way?

Answer 1

Examples 1 and 3 are both acceptable. Example 2 is incorrect. You could change it to "I've forgotten to add them, so I'll add them today."

Personally, I find that when I'm trying to work out tenses, it's easier if I don't use contractions.