Moral relativism as ethics has been largely disproven in philosophical circles. The critism leveled against it is acute and substantiel.
The first and formost problem is the moral progress. If moral relativism hold true than there is no sense of moral progress. We generally agree that society become more just and more humane through history, that today's society not only holds different view on morality than the societies of past but
better ones. that notion need a objective measure of moral truth independent of society, moral relativism denies objective morality, so fail to produce a sense of moral progress.
The second problem is the definition of morality. If morality is culturally dependent and all society consider the norm of that society to be right, than a neccesary deduction is that societies can do no wrong. In that kind of moral universe, to take a extreme example, Nazi would be fully right in conducting holocaust. Because it is the norm of Nazi german society to enslave and slaugter jews, and "What is moral and what is not is defined by the norms of the society in question", than it is perfectly moral for germans to kill jews. Again, in order to make those clearly immoral act wrong, you need a objective sense of morality above societies.
The third problem is dissent. If societal moral relativism holds true, it is alway immoral to dissent. So, in that theory, some of the most repected figures in the history are immoral persons. This list include: Jesus Christ, Gandhi, Martin Luther, Abraham Lincoln, Martin Luther King Jr., John Lennon.....
So, you might want to take cold hard look on this kind of ethics
If you want to know more about morality or you want to become more moral yourself. I'm making a guess against odds here because that's not what most people want. Any introductory book on Ethics would tell you all you need to know about moral relativism.
To answer a more personal question, yes, I do consider myself guilty "every time I drive, every time I purchase a consumer product, every time I waste some food?" I do all of those but I try to avoid them; I consider killing/abusing animals wrong, but I eat meat; I consider taking the skin off another living creature distasteful, but I want leather on my car/shoe. I believe all human life are of equal value, but I won't donate my earnings to save the starving children in africa. I'm not a very moral person. I find being moral very hard, way harder than being a successful citizen, or a fit person. Just like achieving anything, you need to practice it, work on it, everyday of your life. The premise of that is you have to be honest with youself. If you can't lift 100 pounds on you first try, admit you failure, go for a lighter one and work you way up. Or you can leave the gym, tell youself "I'm already fit" and get on with your life. Same with morality, it ultmately depends on your commitment and choice. Most children don't want to be moral, most people what to be the least moral that they can get away with, telling them
how to be moral is a waste of time.