That sketch is good to journal as well as any other observations... especially changes.
You've confirmed that it is indeed associated with your eye, not the telescope or eyepiece by the rotation of your head... it rotates with your head. Note that the viewing condition highlights your eye's pupil-space (exit pupil conjugate upon your eye's pupil), so that could be consistent with your cataract projecting onto your retina, under that quasi-schlieren illumination configuration.
Especially useful is to compare with your other eye. If those manifest differently, that helps the doctor troubleshoot what's the cause.
Although your cataract progression may be typical for your age, it is still considered to be a geriatric abnormality and worth continued, periodic monitoring. The doctor is likely to suggest/recommend addressing it when it becomes annoying or (especially) debilitating.
As you shared, the detached vitreous is normal and expected at your age, provided it did not damage or tear the retina.
It's obviously time to revisit the doctor and have him monitor the changes you are experiencing. As you undoubtedly already know, perceived flashes of light, visual occlusions, etc. are all indicators that it's time to make the call. "Changes in vision" get their attention and an early appointment. Tom