An update, at long last. Things did work out. I was able to get intermittent leave through FMLA. The intermittent leave allows me to take time off only when I need it for up to a year. I had no idea it was even an option until I pressed the HR person at my company. It worked out really well, and I could even accrue paid time off and reserve bank time during while taking FMLA.

The oncologist's Nurse Practitioner filled out the form so well that no one ever questioned me about it again, and my team at work has been very supportive.

For others going through this, please don't underestimate the shock and complete life change that happens after diagnosis. I was such a mess that I had a hard time communicating the situation with my company and colleagues, but that was partly because I had no idea what the situation was. They asked me how much time I needed off from work, and I had no idea. We were still deciding on the treatment and had no idea how mom would tolerate it. I also completely underestimated the emotional toll that it would take on me. Doctor's visits are exhausting, physically and emotionally, for both patient and caregiver.

PS: I'm interested in the long term implications career-wise of taking time off, but it is what it is, I guess.