I think you may be dealing with simple (sic) grief. You've lost a great many people in a relatively short span of time. You barely had time to process the loss of one person before you lost someone else. This would be a shattering experience for anyone, but more so for someone fairly young, which for some reason, I have assumed you are.
That your families had this lack of communication thing going on, then reuniting, and then a death...........I can see how it would be rather easy for you to begin thinking the way you are. You let these people into your life and shortly afterwards, you lose them. But you absolutely must understand that you had nothing whatsoever to do with any of these people passing! What has happened is a terrible coincidence, nothing more.
All these losses have made you afraid of losing other people you love, it's causing you to keep everyone at a distance so you don't get hurt again, it's causing you to obsess about your dad and his job. I think you're smart enough to know that that is a very unrealistic and unhealthy approach to dealing with life, and yes, death.
You are a young woman who has had more than her fair share of loss and in my humble opinion, you're just having a very difficult time, right now, dealing with everything life has thrown at you.
Whether you are an only child or not, we ALL fear the day we will lose our parents. But I'm getting the idea that this thought has become a bit obsessive to you. (?)
I think you are dealing with some attatchement issues and your idea of seeking some help in the form of talk therapy, most specifically with a person trained in grief counseling, would be of tremendous help to you.
You are NOT crazy! And while this IS all "in your head," it's understandable why it would be there. You are, I believe, overwhelmed with unresolved grief, perhaps some guilt and it is manifesting itself as this huge fear of death. (Which is causing you to call your father all the time, to freak when you hear sirens, to "cling" too tightly to your boyfriend, etc)
I'm certainly no psychiatrist, but you not looking into mirrors or windows sounds like a very classic avoidance technique. Not because you're afraid to see these people looking back at you, but to see YOURSELF.
Anxiety can definitely be a by-product of what you're going through.
You seem to have a pretty good understanding of what has lead you to these feelings, now you just need some help in sorting them out, putting them into perspective and moving on. I don't mean to imply this will happen overnight, it's going to take some work on your part, but I strongly recommend you seek some help before this gets further out of hand.
I would also recommend you post to the folks over on the Grief Forum who will understand what you're going through and have some good advice for you. They are very caring and understanding people.
I truly believe with a little help you will get past all these "bad" feelings and move on with your life. And I am very sorry for all the losses you've endured.
I hope you reach out.
Peace
Greenlydia