I've been struggling with the possessive and the statement of existence in the following phrase: 

> 
> 私は今までの私ではない
> 
> 
> 

The easy part is "I am until now"...but then I get stuck on 「の私ではない」. By itself, I understand「ではない」to mean "am not," but then「の私」throws me: "of me"?

How off-base is the following interpretation?

> 
> I haven't been myself until now
> 
> 
>