I definitely isolate for long periods of time when I'm depressed, only leaving the house to do essential things, & feeling ill at ease even doing that. I'm not big in to diagnoses, but the extent of my isolation seems familiar to agoraphobia. I've done DBT exercises to help me get out of the house when I'm feeling this way, but they're seldom successful when I'm really feeling depressed. In other words, no, you're certainly not alone in your isolation.