There are specific traits that introverts share in most cases. If you can related to several or most of these traits then chances are very high that you are an introvert! I previously did a video on this which can be viewed below on YouTube.
1. You feel drained when you're around a lot of people and/or socialize for an extended period of time. Whether it's at a party, school, work or just in a crowd after a period of time you feel the urge to retreat to some alone time to recharge your batteries.
2. You enjoy solitude. You like being alone. You regain your energy when you're alone. You do your best thinking when you're alone.
3. You have a small group of friends or inner circle. You have likely never been in the popular or "in" group. You prefer quality over quantity when it comes to friendships and relationships.
4. People would describe you as quiet or shy (even if you're not). You likely do not often go out of your way to initiate conversations especially with strangers.
5. Too much stimulation drains or irritates you. Whether that's ongoing loud sounds that you did not create, overly bright environments, forced conversations etc.
6. You're very self-aware. Introverts are introspective in most cases. You generally know who you are, who you want to be, your strengths, your weaknesses, your preferences. You may even be so self-aware that you are self-conscious or have lower self-esteem.
7. You prefer to learn through observation. Introverts are often voyeurs. They enjoy people watching, listening and observing others and their environments to dissect what makes things tick.
8. You are drawn to work and professions that are highly independent. This doesn't mean you don't like people or socializing (that's a misunderstanding about introversion) but you prefer jobs that involve occasional collaboration and teamwork but that you're more often than not you're own boss or an individual contributor.