Menstrual period

I’m not sure if this goes in the group but maybe you ladies can help me... I am a first time mommy and I am breastfeeding... my baby is 4 months. I heard breast feeding cans change your periods.. either you don’t get one or they are less heavy and shorter...I got my pd last month, but this month I haven’t even gotten some spotting... is this normal while breastfeeding or could it be that I’m #2 is coming? I’m getting nervous now.. oof it is not normal, what do you suggest?? Should I wait or should I test?