noun : one whose personality is characterized by introversion especially : a reserved or shy person who enjoys spending time alone
We're starting with introvert because it's the most basic of the set. We all know, of course, that basic doesn't mean boring. There are numerous interesting facts about introvert, such as its use as verb, which predates its noun use. Since the mid-17th century, introvert has meant "to turn inward or in upon itself," with more specific meanings of "to concentrate or direct upon oneself" and "to produce psychological introversion in" developing over the centuries.
The adjective introverted is also older than the noun. It's been used since at least 1683, mostly with the "possessing a reserved or shy nature typically with an inclination to solitude" meaning that's contrasted with extroverted.
Meanwhile, the noun introvert has an obscure and technical use meaning "something that can be introverted"—it's applied to such remarkable appendages as the eyestalks of certain snails and the retractile proboscis of a sipunculid worm. That use dates to the late 19th century, while the one you label yourself after taking a personality test dates to the early 20th.