Is it related to headaches?
If the headaches are migraines, the light flashes is related to them. You should see your doctor or a neurologist to evaluate your headaches. If they are migraines, you should have preventive medications.
My neuro has eliminated migraines and diagnosed me with chronic tension headaches
I see. Floater and flashes are very common. Most people experience them at one time or another. most floaters fade over time and become less bothersome. Sudden increase of them is a red flag of the retinal detachment. Otherwise you don't need to worry about them.
Could a prescription medicine such as Adderall effect vision? I am no longer taking it, but took it for 2 years in college. I am convinced something is wrong with my vision, however, after multiple trips to the optometrist, they have found nothing. It's hard to describe what I am feeling. Maybe seeing shadows? Light shadows as well as difficulty seeing in the dark more so than usual.