I am so happy your girlfriend is supportive of your chastity regime. She wants a doctor for a husband almost as much as I want one for a son and she understands that wanking is just a distraction from your studies. She doesn't mind that your Mom keeps your rather small penis locked up almost all the time. It is actually very sweet that she lets you rub your caged little thingy against her leg when the frustration gets too bad.
Are you excited that she is going to watch you get unlocked for strokies today and see your cute little erection for the first time?