well, many of us women have this size disparity...what I was taught early on was, as uke, to go for a feeling of "sticky palm" and not even worry about the fingers gripping if it seemed an impossibility.The palm to wrist contact allows for a real feeling of connection to develop.
As nage, it can be more problematic. You are right that a "death grip" will add tention and conflict. So strengthening your grip will not compensate for a small hand at all. Adapting to work around it is more likely to be successful, IMHO.
For techniques that the "standard" calls for gripping the wrist, I've had teachers show me how gripping the handblade or even the fingers can be just as effective. You might want to check w/ seniors at your dojo for examples of this.