This actually isn't complicated.
David DeAngelo once said "Take two step forward, one step back". That's the motto you should keep.
It's your job to escalate, she won't tell you that it's ok, she's never done it. Easy way to do it is while you are kissing. Start slowly by touching the erogenous zone with your hand. (
http://en.wikipedia.org/wiki/Erogenous_zone)
Then proceed to go for sexual zones, she will probably push you back (that's your one step back), do so and slowly go back towards sexual zones. Just do it slowly and subconsciously, she will start feeling like this is natural.