I don't think you can ever completely transform yourself on film, but if you do your job well, you can make people believe that you're the character you're trying to be.
I'm a character actress, plain and simple... Who can worry about a career? Have a life. Movie stars have careers - actors work, and then they don't work, and then they work again.
It's a scary thing going into the workforce with a $50,000 debt and you've been trained as a classical theatre actor. There's always a depression in the theatre.
Most women's pictures are as boring and as formulaic as men's pictures. In place of a car chase or a battle scene, what you get is an extreme closeup of a woman breaking down.
There's only two givens with choosing acting as a profession: one is you will always be unemployed, always, and it doesn't matter how much money you make, you're still always going to be unemployed; and that you have no power.