grammaticality - "If I were to", "If I was to", & "If I was going to" Which is correct?

Examples:

1. I didn't know if I was going to work next week.


2. I didn't know if I was to work next week.


3. I didn't know If I were to work next week.

I think number 1 is correct, but I would like to know whether is any difference between them. Regarding number 3, I don't think is correct. Can you provide more examples?

Thank you!

Answer

1 and 2 have very similar meanings. To my ears, though, 1 is more matter-of-fact and focused on what the speaker intended to do, while 2 is more focused on what the speaker was supposed to do.

3 is not correct. The past subjunctive here serves no purpose.