If I remember correctly, you need to increase corruption of Amy and friendship with Amy to get further
Bit of a grind, but just make a point of talking to her in the hall as well as in class every day at school....
What are your Amy friendship & corruption levels now?
EDIT: -
Found this in an earlier thread...
- A slut in the making: -
Talk to Amy until you can start to corrupt her - then it needs 25 corruption to meet her in the bathroom to gain the last pieces of corruption
Scene triggers by talking to her in the bathroom with 25 corruption - also needs 15 friendship
NOTE - you need to complete the above for the Amy beach scenes....
- Amy's First Touch
- Amy's First Fingers
Hope that helps