Well then you need to change your attitude and the way you think. Thinking negatively and thinking the worst will cause you to be stressed out. I used to feel unloved, unwanted, nobody likes me and all that, but what helps is talk yourself through that it's just your fears talking. Your mind can be your own worst enemy sometimes and you need to stop making assumptions that everyone doesn't love you. Think of the people that do love you. There has to be at least 1 person on this planet who does. Think of him/her/them and realize you're wrong and people do love you.
If you feel stressed, try exercising. Running, doing weights, walking, jogging if you don't already. What helps me is putting my iPod on and working out. It can relieve stress. Kinda makes you forget awhile your worries and reduces your anger a lot. Make sure you eat and sleep well. All that contributes to less stress.
Find things to do what you enjoy. Do things that can make you happy.