You'll know. Perimenopausal symptoms include hot flashes, insomnia, lethargy, malaise, loss of sex drive, fatigue, Insulin resistance (with our standard american diets), loss of muscle tone, weakness, emotional changes, irritability, mood swings, vaginal dryness, pain with intercourse (feeling like sandpaper during intercourse) and other genitourinary problems.
Near menopause. Periods begin to change, to lighter or heavier, more irregular, usually symptoms of fatigue, hot flashes, flu like feelings, "foggy thinking" may occur, also vaginal dryness, decrease in mood, decrease in libido all can occur.
Hot flashes. The most common complaints of women approaching menopause are related to cycle irregularity and hot flashes. Other common problems relate to decreased estrogen levels, such as vaginal dryness and recurrent vaginal infections. At the age of 22, you appear to have a long ways to go before this occurs. The average age of menopause is 51-52.