Hi girls, my little girl is 4 months old, after giving birth my period…

Hi girls, my little girl is 4 months old, after giving birth my period came in November now there's a delay of 3 days I took a test it seems like a second line but it looks like on the reagent too ??Can delays happen after childbirth? And who had a pregnancy after childbirth tell me how difficult it is generally, how did your pregnancy go and so on