Depression doesn't mean 'sad' per se. Disengagement, lack of interest, etc. still fall into the window of depression. Overuse of addictive things (porn, drugs, alcohol) are also a sign.

Even if it is for a single session, I'd suggest talking to a professional therapist. If they're local, they even may have great ideas on things you may enjoy out of the house/connecting to other human beings in person. They may also suggest medications; I strongly suggest if you go the med route to see a psychiatrist over a primary care physician; psychiatrists simply know their stuff better/can monitor you more effectively.