If I get an ovarian cyst 2.5cm does that mean that the egg did not release this month or whenever it occured&formed? How long does it take to form?

No. Small ovarian cysts are extremely common in young women. It does not necessarily mean that you did not ovulate. Many small cyst will resolve after 1 or 2 normal cycles.
Correct. It takes about two weeks for the egg to ripen to ovulation. Ovulation is triggerred by a horone spike. A variety of difficulties can occur to prevent ovulation. If this occurs on a regular basis, often characterized by markedly irregular menses, a gynecologist can help can help sot it out.