Is Irregular Menstruation Normal During Lactation?

after delivery i got one period in 57 th day of delivery then i didnt come my menustration.now i am breast feeding my baby.my pregnancy urine test is negative(1 week)before i checked.can i take duphastone tablet is it have any side effect or this is normal in the lactation period(no menustration) is it necessary to do bloodtest also for conforming pregnancy