It sounds like you are going through a period of self-doubt, and I think that's something all of us go through from time to time, especially when we've made, or contemplate making, major changes in our lives. It doesn't sound as though you're either moving in the wrong direction or letting life pass you by. In fact, it seems to be quite the opposite--you've been making "alot of EXTREMELY DIFFICULT but Totally positive changes In my life", and that's wonderful, but it's also stressful and it can lead to feeling somewhat emotionally overwhelmed at times. That's why you might feel as though you are about to burst into tears, or feel short of breath, or suddenly consider everything in your life to be totally wrong.
You've been pushing yourself rather hard and you may just be temporarily emotionally overloaded. You need to take a breather, back off from thinking about making all the self-improvements, and just relax for a bit. Try to refocus on the good things in your life since you say, "Everything in my life Is Going Rather well and i Feel like Im pretty happy". That's a good place to be, so enjoy it. Take some time to smell the roses and appreciate what you already have. You do feel entitled to be happy, don't you? Part of happiness is a feeling of contentment. Even though there are more changes you want to make, allow yourself to feel content with what you've already been able to accomplish. Give yourself permission to feel happy about the positive things in your life.
You've gotten some good advice about relaxation techniques in this thread, and you should try them. Deep breathing exercises are great, you can do them just about anywhere, and they will help you to relax if done properly. Make sure you do them slowly, and practice them.
Talk to yourself about your feelings and thoughts--out loud if necessary. I sometimes do this when I am driving in my car. If you know that some of your feelings are illogical (like everything is wrong about your car), talk to yourself the same way you would talk to a friend who had such feelings. Tell yourself you are being silly or foolish to feel that way, and try to laugh at yourself. Promise yourself a Ferrari after you hit the lottery.
You can control how you feel and think about things, because you can always alter your attitudes. For instance, while your life might not be perfect now, it isn't all totally wrong either--it's simply a work in progress. There is something to be said for seeing the glass as half full rather than half empty, so try to keep your attitudes positive and optimistic. No matter what you decide to do next, the world won't come to an end if it turns out to be a bad choice, you will always have another chance, and another choice, somewhere down the line, so try to keep things in perspective.
You already found one good technique for sorting out your thoughts and feelings--making a list or writing things down.
The list Like INSTANTLY made me feel better and it was like i suddenly had control over how ive been feeling and like i was able to change it.
And you know you have control over your feelings, and that's a wonderful insight. You can logically and rationally examine your emotions and thoughts, and you can change them. Writing things down helps to make them more objective, and it helps to scale them down to size. What you think helps to determine how you feel, so continue to write things down, and think them through, and try to be positive in your attitude. Consider keeping a daily journal if you think that would be helpful to you.
Even good changes in our lives can sometimes throw us for a loop. Change is unsettling, it creates anxiety because it forces us to confront the unfamiliar. But that's a good thing. You may just need some time to adapt and adjust to where you are at this point in your life. So, give yourself a breather, learn some relaxation techniques, appreciate the good things in your life, and just keep moving forward one small step at a time. Basically it sounds like you are on the right track. You know that, "ive worked hard and have alot to be proud of", so keep reminding yourself of that.