for me I never wondered about why I wasnt outgoing... everyone is different even among completely normal children some are outgoing and some are shy, or introverted..

sometimes shy/ introverted children when they go through puberty become outgoing and sometimes outgoing/extroverted children hit the teen age/puberty years and become shy and introverted.

the puberty years are full of a changing body where everything that makes up a person is changing, sometimes those bodily changes, physically, emotionally and sexually cause teen agers to feel many thingas like fatigue, sadness, confusion, rebellion... some dont get a handle on all these changes and side effects from all the changes until they are between the ages of 21-25.

my suggestion if this continues to bother you contact your medical doctor. they will be able to explain more about why a 17 yr old will feel like you do during these developmental years. they can also help you to discover whether you have more serious problems that may be causing these symptoms like anemia, sleep deprivation depression or any physical or mental health issues.