The only way to really get officially dx is through a professional. I believe that pessimism and hopelessness are signs of depression or at least heading in that direction. Although chemical imbalance is definitely a cause of depression, it is just one cause. Chemical imbalance is also caused by the foods we eat, medications we take, etc. so it is also environmental. Many other factors also play a role such as stress, illnesses, drug use, losing a loved one, etc . Many studies have been done with IBS alone and concluded that more than 90% of IBS sufferers also have some sort of psychiatric disorder with generalized anxiety disorder being the at the top followed by depression as a close second.
IBS, Diverticulosis, GERD, Disc Degeneration
"If you don't like something change it; if you can't change it, change the way you think about it" - Mary Engelbreit