Is it possible to not get enough blood/oxygen to your brain? i feel light headed at times. wobbly head & get headaches a lot

Can be helped: Your description raises questions of a migraine etiology to explain most of your issues, but other explanations could be considered. However, would doubt insufficient blood/oxygen to brain. Still, have your doc check for postural hypotension just to be certain. You may be have anti-cholinergic reactions to your nortryptyline. Have your doctor reassess.