If vs If used with OR NOT

Question

I don't know if she loves me.

Vs

I don't know if she loves me or not.

Could we use only if in the above sentences, without the use of "or not"?

What's the difference in their meaning?

Answer 1

Actually, there is no difference between them, but, we usually use "if" without "not".

I don't know if she loves me.

I don't know whether she loves me or not.

This is just a difference of usage.