You are different from everyone else, even if you don't know it. You are an individual :) No spell required.
If you wish to change your physical appearance, you could start a diet, perhaps work out, or maybe do the opposite. As far as changing hair color and eye color, there is hair dye and color contacts.
You are special just the way you are, and if you don't feel that way then make it so you do feel that way.
I know this isn't what you wanted to hear exactly, but it is my own truth that I am sharing with you.
Your 'horrible life' is you living in the past. It is a state of mind. Yes, it happened, and yes it sucked, but it is in the past. It is over. Look ahead, enjoy now. Live for today :)
Well, most of the people on here do not believe in shapeshifting physically, however there are spells that can help you change physically and you could try them out, or I suggest going to a shaman, a shapeshifter, or someone that has that ability to help you learn how to shift. even though I personally don't believe in it you could try going to a professional to help you shapeshift if they believe in it like you do.
You cannot physically alter yourself in such a way. It is not possible. The human body cannot be manipulated like that, even with the use of magick. No spell or chant can alter your DNA and such to that degree.
Having said that, you do not need a tail or claws to be special and different. Stop to consider that there is only one of you in the world. No one else is like you. You are unique on your own without any alterations to yourself. Learn to love yourself for who you are instead of seeking out ways to change yourself.
I know how you feel as I have been in situations in my life where I feel that I want to be someone different or want to change in such a way that it might make me look and feel like I'm a different person than I was in times past. If this is the case then let me assure you that you can change the outside all you want and it won't make much different to how or who you ate on the inside. But there is great news! The path for what you seek is the same. If you truly wish to gain enough power to alter your physical features, you first have to start from within. In magic, the power to change or alter things comes from the power within yourself. This includes working on your willpower, focus, visualization, self confidence and learning who you are, how you truly behave, how you learn, accept your weaknesses and strengthen them, acknolodge your strengths and use them to your advantage as well as many other things. The advise and knowledge the others above have shared are true and very wise words indeed. Focus on what you like about yourself and the good things you remember from your past. Write down what you want to feel or look like on a piece of paper in as much detail as possible. Start reading and learning about good meditation techniques, energy manipulation, spells, wizards (or whatever magical type you feel drawn to), occult sciences and anything that any of those topics tell you to read on in order to get a firm grasp on the topic. Come back to your list you made each week and mark off the things you have suceeded in accomplishing and write other things down that you might have found that you need to learn about or work on. If you find that your thoughts are getting worse or you feel more depressed then you need to talk to your parents or a councilor right away. If, in a month, you still want to change then come back and I will give you a spell to cast. The trick is, is that you have to have confidence in yourself, be ablke to focus and visualize intensly and have a good basic knowledge of how magic works to be able to cast the spell and have it work. You can find many threads and info on this site to point you in the right direction. Read the articles and search the forums to get the ball rolling.
Sadly, no matter what anyone says, there is no way to truly effect a permanent change your appearance through the use of magic. Those who tell you otherwise are giving you false hope. I am sorry that your childhood was so miserable that you don't like yourself the way that you are. Perhaps that self-hatred is what you need to spend time working on rather than superficial changes of appearance.