Welcome to the forum but sorry that you had to find us.
My wife got diagnosed with extrahepatic CC two years ago, a few short days after she turned 44. Same age as you.
Like you, she had CT, MRI, ERCP with stent placement, and a brushing biopsy. The biopsy came back suspicious for cancer but inconclusive. This is very common. The brushings collect a very small amount of tissue. The pathologists have a hard time confirming or ruling out cancer based on the tiny sample they have to work with.
If all other evidence points to CC, the surgeons may recommend surgery in the absence of a positive biopsy. That's what happened to us. We gave consent to Whipple surgery even though cancer diagnosis wasn't 100% certain. CC was confirmed by the full pathology report *after* the surgery.
If your biopsy ends up negative or inconclusive, ask your doctor's opinion about the following two options:
1. SpyGlass biopsy. It's an endoscopic procedure similar to ERCP. SpyGlass biopsy uses forceps, so it's able to collect a larger tissue sample.
The downside of SpyGlass: a negative result cannot rule out cancer.
2. Endoscopic Ultrasound (EUS). Again, it's an endoscopic procedure similar to ERCP. My wife had EUS done after her biopsy turned up inconclusive. EUS sealed the deal for us. We gave consent to Whipple the day after EUS. My understanding is that EUS is not a very common test. If you end up doing it, try to find a very experienced doctor. That way you can feel more confident about the results.
Welcome again. Please keep us posted.