Im prone to getting suddenly very scared by very minor things such as sudden loud noise and stuff like that. does being in a fight or flight mode a lot really causes adrenal gland burnout?

Chronic anxiety is very common and also very difficult for patients. If you are aware of your own anxiety to this degree I would suggest seeking an opinion about treatment. Nothing good comes from chronic anxiety and many bad things do!

It is not feasible to provide a meaningful opinion without taking additional history, physical examination and may be some tests. It would be prudent to see your doctor and discuss if you may be depressed. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water. Wish you good health!