Visual Disturbances- Migraine Aura.

For the last couple of months, I'm seeing some kind of visual disturbances like seeing a white light , not very bright but a noticeably white light in different shapes, then increased blue field entoptic phenomenon, then a kind of black shadow or white light in dim light etc. I have previous history of migraine. I have consulted an ophthalmologist and done various tests like vision, slit lamp, tonometry, HFA, ERG, Autofluorescence etc but couldn't find anything wrong. From childhood I've the problem of seeing afterimage when looking at bright objects in dark color like red or black. These symptoms lasts only for 3 seconds. My ophthalmologist concluded that this is probably migraine aura. But I'm having these symptoms everyday like when I wake up, then looking at dim light and many times a day. Sometimes I'm having one sided headache. But I'm seeing this visual disturbances everyday without headache also. please advise with your thoughts of what might be actually happening? Thank you