Well, you got it right near the end....................your painfully shy......not anisocial. Not everyone can be the "life of the party" or .Mr/Mrs Popularity.............but if that's part of your goal...................watch carefully someone you admire and emulate them..............how do they approach people?do they show interest in the other person or is it all about them?
It's normal to want a relationship, however at this age, I'd be careful what you wish for..................there's high emotions, power trips and little games played especially for the novices.................all about learning and growing up, but not an absolute need for the ups and downs of teenagers.
All for improving self esteem................get the drivers license, get the job..................part time.................thru friends/family.............thru the school..................if you want it bad enough.............you'll find a way and do it!
For shyness, a public speaking course.................like Toastmasters............but ultimately it doesn't matter which course or skill you acquire as long as you do something..................remember the last time you did something new or mastered some skill.......................how did you feel?on top of the world?............................and how does it feel to sit around doing nothing?absorbed in self pity?....................get moving...................and the rest will follow