I'm so sorry you have to go through this and understand your fear. The waiting is always the worst part.
Most nets are slow growing so there isn't always a sense if urgency from the medical field (though there always is in our brain)
Have you had a biopsy? The ki67 score will give you an idea of how aggressive it is.
When you say the ga68 was negative, did the known pnet light up?. If so, and nothing else lit up, I would consider that encouraging. Have you had a pelvic mri?

For some context for you, my husband was diagnosed with a 10 cm pnet on the tail of his pancreas and more than half his liver covered in tumors. 18 years later and many surgeries and treatments, he's still here and living life. As I said, this is typically a slow growing cancer. Our original net specialist discussed it in terms of a chronic disease and he was right. Its a lifelong game of whack-a-mole, but there is more options and hope now more than ever.
I pray for peace in your heart and an excellent outcome to your surgery.