10 m pp & period is late!!!

Ok... so im almost 10 months post partum. My husband and i have been active but rarely as my child is quite demanding and clingy to mama. But my period is now a week late, which before my son wouldnt worry me.... now im paying closer attention cuz ive been pretty regular. I took a test last weekend just cause i had a weird feeling... negative. Should i worry? Should i retest? Ughhhhh... i was told i most likely wouldnt have kids now at 34 i have a 9.5 month old baby boy who is my life... but am i ready to add to that already? Help mamas!