Is the absence of semen discharge after the appearance of other signs of puberty normal or a disease, especially when following a vegetarian diet?

The signs of puberty for a male are: the emission of semen, or the growth of coarse hair around the pubes, or completing fifteen years of age. For a female, menstruation is an additional sign. The fulfillment of just one sign is sufficient to determine puberty. Since the questioner is sixteen years old, this indicates his puberty, and that he has become accountable and responsible, based on the Prophet, peace and blessings be upon him, saying: "The pen is lifted from three: from the child until he reaches puberty..." His condition of not experiencing seminal emission might be a medical issue or a natural variation, and he should consult a specialized doctor to verify this.