Ty decided it might be best to start off by changing himself. And since he felt anxious about his maturity, maturing himself seemed like a smart option. He could get himself free of the hormonal angst of still developing and just be an adult.
The fantasy was appealing to him, and he soon found himself fixating on it. He willed and spoke the wish- "I wish I would age to 18 years old." A warmth ran through his body as his pubescent development began to accelerate. Ty felt his clothes starting to get too small for him, and pulled them off hastily.
He saw his body hair starting to thicken all over, and felt his arms and legs lengthen and grow more lithe. Catching his reflection in a mirror, he saw his jawline firming up and noticed his muscles had grown thicker. He had grown several inches taller and appeared significantly more mature.
Probably the most noticeable change to him, however, was how his penis swelled and his balls seemed to expand subtly. He had the six-and-a-half inch, fully developed shaft of a grown man, one that anyone would be keen to have inside them.
Ty stared at himself in amazement, weirdly starting to feel more settled in this body. He felt kind of more used to its hormones than he had as a teenage boy, and felt more comfortable in his sexuality. However, he noticed he still had the clothes of his 15-year-old self, and wished his wardrobe to alter to match.
To his relief, he saw his wardrobe alter, growing a few sizes to fit him while some of the things he had T-shirts of changed, reflecting his older self's interests. Ty was about to pull some clothes out to get dressed, but then it occurred to him that if he could transform his body like this, maybe he could change himself more...