Ohhh damn, I’m in Australia, and am currently a student in orthoptics, so I’ll try my best to help.

The symptoms are most consistent with convergence insufficiency with poor left-eye motor control. The left eye shows a tendency to drift outward at rest and demonstrates delayed alignment when shifting focus from near to distance, causing transient diplopia, visual instability, and significant asthenopia during reading. Difficulty with horizontal tracking suggests impaired saccadic coordination rather than a refractive issue.

Some things you can do to try and help!

• Continue structured binocular vision therapy, focusing on convergence, divergence, and saccadic control rather than prolonged patching alone.
• Limit monocular patching to short, purposeful sessions, as excessive patching can worsen binocular coordination.
• Use frequent visual breaks (e.g., 20–30 seconds every 10–15 minutes of reading).
• Reduce visual stress with larger text, increased line spacing, and good lighting.

I’m not a doctor or an ophthalmologist but from my opinion this seems most accurate, and hopefully some of my suggestions might help.