Very occasionally I'll feel a reflux episode that hits the back of my throat when upright.
The sour taste in the mouth? I get that each morning, or if I take a nap during the day...since I don't sleep well at night. Doesn't matter if I'm in bed with my wedge, or in the recliner.
The only way to diagnose your reflux is to have a pH study, and that will tell you how many episodes, how frequent, and to what degree. 95% of individual reflux episodes go unnoticed by the patient, unless open erosions are present in the esophagus.