Hi there, First off, I'm sorry you haven't gotten a reply until now! Ill do my best to provide some insights/help. =)
Second, I can understand where you are coming from in terms of moving a lot. I've moved 11 times in my life already. I think you might be going through something I went through when I moved a lot, and that was making sure I didn't form too close of bonds with people, because chances were I was going to move away from them. And if we weren't super close friends, it was that much easier to let go, and it saved me that much more pain. I think it was a way for me to cope, and you might be doing something similar, even though it may be subconscious. I also think that since you've had some let downs in the past, and coped with them pretty well, you're a strong person and you're just finding these things easier. It doesn't mean you're a bad person. I don't find some things as upsetting as most people do, and I attribute it to all that I had to deal with as a child. It could be the same for you.
I also think it's hard to move when you're in the teenage years, because you are starting high school, and sometimes pressure and stress can build up, and that can just make you feel numb as well. I go through periods like that still. Plus you've had quite a lot to deal with in your past which can just contribute.
In terms of you feeling guilty, I think it's normal to try to move on and concentrate on building up your new life. It's the here and now for you, and it's what is most important. However, there is nothing to say that you can't keep a little contact with your old life. I'd especially try to make some contact with your mother, even though I am guessing you have a lot of resentment or anger towards her. Even if you guys just talk once a week, or a few times a month, I think it would be nice, and probably in the end beneficial, to have some contact. Maybe call your friend once in a while too. Sometimes it is better to make an effort on these things, even if you don't want to - just for the other person.
I hope this helps you a bit, and if you ever want to talk, feel free to PM me, okay?
Take care. =)
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if ever we meet on your side of the stereo,
I will pretend I know not of your flaws,
or even the way that they mirror my own.