Is my period starting?

I gave birth 8 months ago and got my period a month later and have been regular ever since, but this cycle my period is late by 3 days and for the past 2 days I have been having pink tinged stretchy discharge, its almost clear. I have been taking tests every morning from 6 days before late period but they have all come back negative. If anybody has experienced this could you please let me know whether it was the start of your period or you were/are pregnant.