Where should I top this lady?

I want 2 colas, maybe 4
Rocklock - 3 weeks old

If you want 2 colas top above first true node, if you want 4 top above second. Seeing that your plant has at least 7 nodes i would top above the second or even above the third to get 6. Don't worry about loosing more than a half of your plant coz you can use it as a clone.

I don't think I can cut her

Well, that's what topping is all about. If you prefer you can pinch her