Since you have been so candid with me about your negative feelings, disappointment and self-doubt, I would be remiss if I did not answer in kind. I am concerned that you have been depressed, perhaps clinically depressed, for some time. Motherhood should not be experienced as 70-80 percent struggles and hassles. Moving dejectedly through your life as if it's "one long battle" suggests that you have been incapable of feeling optimism, joy, and a sense of mission and purpose in your life. It appears that you may have been feeling that way since your child was born, like you experienced post-partum depression that became a continuing, endogenous depression.
When you speak of your child's behavior (the behavior that's bothering you so much), it's the type of stage developmental behavior expected from kids at this age and stage. You also believe that parenting "gets worse" as kids get older. You seem to be saying that having this child has stolen your life and has left you with nothing but a struggle to get through each day.
I won't pretend to know what the underlying causes of your ongoing depression are but I will strongly recommend that you seek out individual therapy right away. A group such as Parents Anonymous would also provide ongoing, non-judgmental support and understanding. Your malaise, anger and lack of joy are not going to disappear on their own. You, your child, and your husband deserve better lives. You are not a "bad mother" because of what you feel. There are very good reasons why you have become overwhelmed and depressed about being a mother. You must discover what has robbed you of your former joy. I guarantee you the answer will not simply be, "Having a child."
Please take the first step toward getting better and get this professional help. It takes courage to face these demons but you know that you must. Ask your husband for his support, as I am sure that he has been worried about you for some time. Would you contact me when you have taken this step?