Question...Feedback appreciated

Ok, I know I am not supposed to overthink things, but I am still trying to pinpoint exactly what it is that has caused my symptoms.

One thing I have noticed is that my brain seems to have trouble with alot of things going on that it has to focus on at once.

For example:

I am sitting at my desk at work right now. I was feeling sort of detached. I then decided to turn on some music. So I am now listening to music as well as typing emails, etc. Well, when the music is on I detach even more. And if someone walks by my office or comes into my office, I detach even more. Its like my mind is protecting me from activity as it happens.

Another example:

When I am in the car, I may feel sort of detached. If I then stop to pick up my friend and he gets into the car, I detach even more. Or, when I get out of the car and go into a store, I detach even more.

Another example:

The grocery store. I may be feeling sort of detached, but then walk into the store and see all the people, the bright lights and all the different items I need to concentrate on. So I then get more detached and lose focus, concentration, etc.

Another example:

I will be sitting in my apartment by myself. Then my friend comes over and when he/she comes inside, I detach even more.

Another example:

I may be sitting at my desk and when I get a new email it makes a sound on my computer that alerts me that I have a new message. Well lately that sound will kinna make me jump. Or when the phone rings, it makes me jump.

Another example:

I went with some people from work to get some food after work yesterday. Well I felt half way decent on the way there. But as I got to the restaurant and sat down with all the people from work, I got more detached and couldn't concentrate, focus and felt detached from my voice.

Another example:

I was feeling halfway decently connected and then left my office to go to our St. Patrick's Day party at work in a conference room. When I entered and was surrounded by alot of people and saw all the food and noticed the extra noise, I all the sudden became so detached.

Final example:

Yesterday, my boss asked me to help him escort some people back to a meeting in our large conference room. When I went to the front lobby to get ready to greet the people, I was surrounded by my boss and the secretary and other people coming in. I then became more and more detached.

Anyone seeing a trend here? It's like my brain can't handle changes in environments, people, noises, etc...etc. And then to protect itself, it Depersonalizes to hide from it. But little does it know, it is a horrific feeling, which has caused me to be extremely depressed. Now I don't ever really have a panic attack, or sweat, or have a pounding heart, or get dizzy or light-headed but I become sooooo detached and trapped inside my own head that it is horrible! And it's almost like my brain is doing it on its own, not because I am doing it.

Any thoughts? Your feedback is appreciated. Thanks.

Kelson