First of all, CONGRATS on losing 66 lbs! I have about that much to lose, so I love the fact that you've lost that much weight. No wonder you don't recognize yourself anymore!
I have not lost a significant amount of weight YET, so I haven't yet experienced an "identity" crisis like you are going through right now. However, I will say that you are still the same exact person that you were before....with MUCH healthier habits. You still have the same memories, but now you have the chance to make new, even better ones.
So, my advice is just to look at yourself as an improved version of your old self. That person is/was still YOU, and you can't forget her, because you have to remember her to remind yourself of how far you've come and let her be a lesson learned to never let yourself be overweight/obese again.
Is there anything from your "old" life that you still do? For example, I like to read, write, take walks, etc. and losing weight is not going to change that about me, even though the person looking back at me in the mirror will look different than she has for the past 23 years. I am not defined by the unhealthy habits that made me fat. You aren't either. Even if you DID define yourself by them, use this weight loss as a chance to re-define certain areas of your life. That "pretty nice girl" you used to be didn't go anywhere....she's still there, and she's the one who gave you the determination and drive to change your life. SHE grew, while your physical body shrank. Now you just need to re-acquaint yourself with her. Personal growth (in the spiritual sense, of course
)should be scary but it's also exhilarating, necessary and beneficial.
Did any of that make sense? I hope that some of the girls in your situation who have lost a lot of weight can give you better advice. Hopefully when I reach goal by the end of this year I will be able to take some of that advice if I find myself in an "identity crisis" like you.