When I first read your letter, I wondered if you had visited your personal physician for a checkup recently. I am not a physician, but I am aware that your irritation can be a symptom of many things, among them a nutritional disorder, neurological damage, or medication interactions. So I would advise you first to seek the advice of a medical doctor.
You write that you did not always feel angry, edgy, and unfriendly, and I wonder if you can trace back to the time when your feelings and your behavior changed. Tracking this down might give some clues about what it is that has gone wrong.
You may not have a big social circle, but are there a few friends or relatives to whom you could turn for help? They might have ideas about when, and even why, you changed.
You ask if you are depressed. It sounds like you are, and anger, as you might know, goes hand-in-hand with depression. Anger is even an underlying factor in the development of depression.
You say you are nitpicking and edgy. Who are the people most affected by these qualities? Do they have something in common?
Funny, one of the first things you wrote was that simple questions bug you, so I guess I’m bugging you as you read my reply, because I’ve asked you a lot. So rather than ask anything else, I’ll suggest that after you visit your physician you make an appointment with a therapist, who will ask you to talk about yourself, probably ask questions that annoy you, and who will request that when you’re annoyed you say so. The therapist will also ask you to report when you think the conversation has gone stupid, and you won’t have to worry about being offensive, because the therapist won’t take it personally, and that will help you, eventually, learn how to be the more likable person you say you used to be.
I hope you find your old self soon, and that when found it’s even better than you remember.