Help!! I am insecure and destroying everything in my path!!?

I think you're the only one doing the comparing between you and your brother. You have referred to yourself as "just a nursing major"--JUST?! Be proud of yourself. Stop telling yourself you're not good enough and don't deserve to be happy, and have a serious relationship. Focus on the positive. Really focus on what you're thankful for and, what you want (visualize). Don't allow yourself to think one negative thought about yourself. Think and say only positive things for two weeks and see if you feel a change in the way people treat you and the way you see yourself and the world around you. You can do it! Good Luck!