I think you should try an old trick of looking at your creation in a mirror. That can give you a different view than you're used to and you may see the subtle changes you need to make her as perfect a likness as possible. As an objective observer, I can see Marilyn emerging, but she's not quite there. Portraiture is a very subtle art. I did pastel chalk portraits from photos, when I was using normal media. It's not as simple as it seems. I'm going to try to extend my portraiture to Poser in the not so distant future. I think it would really be a challenge. Meanwhile, you've got a good start.