hi nummy. I think the only thing your lacking is confidence. You can buy or borrow self help books which really help with self esteem, assertivness etc.

When i was 16 i felt like an ugly aqward freak painfully shy and had a serious eating disorder. Its not that i wanted to be skinny, i wanted to fade away into nothing. I didnt fit in with my family, they bullied me and i didnt want to be here in this word. Out of desperation i got three self help books from the library related to improving self esteem and confidence. I worked on the exercicises everyday and gave my self really small tasks do on a daily basis such as ask my boss if there is overtime, say hello to someone . It actually worked as i put so much effort into it.
Im glad your sister stuck up for you, i had no one. I was completely alone. Things will get better if you want them to. Im sure you look much better than you think you do. Good luck and keep posting. Feel free to pm me any time