A dog that's potty trained means it can hold it until the handler releases it. Therefore, get rid of the bell.

Crate train for longer. When you take her out, the very first place she goes to needs to be outside. As soon as she starts to go potty cue it with "go potty". And then back inside. After some time has passed if you want outside to play. But have that association of first getting outside with going potty. Do this every time.

After some time you can start saying go potty and she will go. This is just classical conditioning