Late period, negative test

My period is 1 week late and I tested negative for pregnancy. Should I wait for another week and test again? Anyone else experienced late period, tested negative and then positive in the next few weeks? I have been getting my monthly period as usual after I gave birth. This should be my 8th period and was due to come on between 27-30 Aug as I was usually 1-3 days late. Feeling hopeful if I could be pregnant, cause I really want another baby (coming 11 months post c-sect). My symptoms are probably just a little bit of cramps and a massive headache yesterday (4 Aug) and today. #advicepls Update: I missed my period in Aug and it came on 14 Sept instead. Wasn’t pregnant at all. Before pregnancy my period was always irregular.