1. Being on display while fucking you. You may want to show her there are other positions that she can enjoy your ass in. For instance, you can ride her girlcock…this puts the onus on you to be the active one. Another is to have you on bent over the side of the bed and she can stand behind. These may help ease her into it until she finds her confidence.
Other than that, just encourage her to play with your ass more…perhaps she can manually fuck it with a dildo to see how hot it gets you!