It's a long question. is it possible for a female teenagers to have internal male genital and what can be the symptoms?

Unlikely: By the time the teenager gets to this age they have usually seen a doctor. Schools require vaccinations. Somewhere along the line a good physical at birth and certainly up to now would have identified this unusual condition. It might be possible but the chances are very rare that a female would have an internal penis.

46 XY female: Androgen insensitivity in an outwardly appearing female can in fact be a genetic male. It is due complete absence of a hormone which makes developing fetus develop male stuctures. Such people can have perfectly normal appearing female genitalia with labia and clitoris but will lack vagina. They have testes inside the body or in a groin hernia. Never menstruate. Jamie-Lee Curtis is a prime example