Is my menstrual cycle normal? one month is 24, the next 29, then 28, then 22, then 23, then 30. why is this/is it a cause for concern?

Normal variation: The variance in the cycle lengths are a function of whether that cycle produced an egg or not. Delays in ovulation tends to lengthen a menstrual cycle. The use of hormonal contraceptive methods will end that variance. If your cycles become longer than 35 days consistently, and you are attempting pregnancy, then see a MD for assistance in ovulation. Post first period cycles are often irregular.