is this normal? na after 1year giving birth about period

HELLO MOMMIES, as a first time mom and first cs delivery. is normal lang ba na irregular ang mens ko kase 21 days na akong delay, but started ng period ko is oct 28. and active kame ng bf ko at nakaka 1round lang kame sa isang araw but naka calendar method kame kase plan namen mag second bb, at wala akong any contraceptives. And everytime na mag ppt ko is always negative naman. correct me if i wrong po or may experience dn po kayo?😊