Do I have low vision with thin optic nerve?

It might be a good idea to seek medical attention since you're experiencing low fever, sore throat, etc.. Given your history of migraines, these symptoms could have various causes. If your symptoms are severe, worsening, or causing significant distress, it's advisable to seek medical help promptly.

Seeing flashes of light or "lightning" in your peripheral vision can sometimes be a symptom of an eye related issue. However, stress and anxiety can also cause visual disturbances, including perceived flashes of light. Meantime it may be helpful to practice stress management techniques, such as deep breathing exercises, mindfulness or meditation. If this also doesn't help then visit an eye specialist to get it checked.

Your eyesight has changed a bit with a measurement of -0.25D. This might make your vision less clear and give you sore eyes or a headache. If you spend lots of time looking at screens (like phones), these symptoms could get worse than they already are. To protect your sight, attempt to keep screen use down to 2 hours everyday maximum and take breaks every 20 minutes or so where you focus on something in the distance. You should still wear your glasses as directed by the optician as well. 

This issue is called myopia. It occurs when your eye­ball is too long or the cornea is too curved. Howeve­r, wearing glasses with the right treatment helps correct this. You nee­d regular eye e­xams to check your vision.

Yes, of course! Retinal pigmentosa is a visual disability that happens when the cells in the retina do not function properly, thereby leading to a vision problem. Symptoms include difficulty in seeing at night and side vision loss. It's mostly a genetic disorder, and thus it commonly appears in families. Retinitis pigmentosa is yet to be discovered with a cure. However, using sunglasses and low-vision aids can benefit the management of the symptoms.