My cycle was 23 days but for past few months dropped to 19. no spotting/pain, or any other symptoms, just regular period. recent pap (may) was normal. is this worrisome and what can i do?

Premenopause maybe: Shorter but regular cycles can start years before menopause. But because you are so young, it might be another related hormone change - see your doctor.

Inconvenient: Normal cycle length is 28 days +/- 5 or so days. 19 days is a little short. While this is not a dangerous problem it is certainly inconvenient. This may be a problem if you are trying to conceive. There are ways to correct the cycle length depending on your reproductive plans. Talk to your doctor. I am glad the pap was normal. It has no relationship to cycle length.