I am feeling cramps like in periods, but my periods are finished now. it is very slight but noticeable? is this sign of infertility? i am 21 yrs old. please explain

Cramps: no thats not a sign of infertility, may need to check your urine.

Pelvic Cramps: Pelvic cramping is not uncommon and often does not have a clear cause unless it's something that is severe or recurrent. You're young and as long as you have regular periods, I would not be concerned about your fertility. Keep a calendar of your symptoms and see a gynecologist if you continue to be concerned. This is very likely normal. Hope that helps.