[americuadorian]

She is certainly one that you do not want to let get away. However, I must ask, do you talk? I mean really talk?
Do you discuss important matters, such as bills, rent/mortgage, the future? Talking about your sexual interests is equally as important as discussing where you see yourself in 1 year, 5 years etc. Business, friendship, or marriage - communication is the key to the successes of any type of relationship.
If you are not talking openly about what you like and do not like, how these experiences have been enjoyable for you, then you are not being honest with her. This form of dishonesty usually drives one to cheat on their partner in order to fulfill hidden desires. Do not present it to her as if it is a demand and you should expect her to think about what you have said for a good deal of time before expect her to answer. And when she does, she will start the conversation. You just have to plant the seed. Let her know that if it is something intentional or not, that it is okay.
Most people simply need validation of their feelings to stretch their limits. Often in the case of women, who have been degraded and insulted for having sexual desires, they only need permission in order to free their mind of the many societal norms. What you feel is okay. What you desire is okay. Knowing that you will not be judged harshly is very liberating.