Eye flashes from second trimester.

I am having weird white ⚪ circle like flash or u can say a light floating (going upward to downward) in the side of my eyes.. They are noticible this happen to both eyes but not at the same time.. Never in the middle but in the side of my eyes like they are not in my vision but they are present in my eyes ... This is happening to me from second trimester of my pregnancy till now four month postpartum... I m really confused I saw retina specialist two times she said my retina is fine.. Then why is it happening to me i m really worried.. And one more thing it shows no timing sometimes this happened whole day like 20 times and sometimes like more than 20 or less then 5depends on my day and it really got triggered by my stress