Having Visual Disturbances Frequently.?

For the last couple of months, I'm having some kind of visual disturbances like seeing a kind of white light not very brighter in either of eyes which lasts for 3 seconds, then increased blue field entoptic phenomenon when looking at brighter objects in sun light , seeing a small black shadow / small white light as mentioned above in dim light etc. These symptoms are occurring everyday frequently. I have previous history of migraine and sometimes I'm having one sided headache also. I have consulted an ophthalmologist and gone through various tests like vision test, tonometry, slit lamp test, fundus examination, HFA, Electroretinography, Autofluorescence Test, colour test etc and all the results came out normal . Finally doctor concluded that it's migraine aura most probably. But I'm having these problems consistently like every morning when I wake up then many times a day. I'm very concerned about this. Could you please advise me with your thoughts of what might be actually happening.?