Breastfeeding!!!!NO PERIOD!!!?

I know if your breastfeed you dont really have a period!!!and noo i aint pregnant!!!! I just want to know how long it lasts i been breastfeeding for 7months now n havent had a period for like 5months!!!my friend just got her period after 6months without it she breastfeeds as well!!! Has this happend to anyone????if sooo please tell me about it i'd really appreciate it !!!thank you for your time!!!