good morning ladies

4 days late with all pregnancy symptoms... (breast tinderness, nipple discoloration, discharge, cravings, pressure in lower abdomen, nausea, weight gain) 
i've taken 3 tests and all came back negative.. yesterday they gave me an ultrasound because of my previous history of repeated negative tests while pregnant with my first son. she said my endometrium is thickened and cervix is closed.. but since it's still early they want me to come back in 2 weeks for another ultrasound to be sure..
this morning i saw bright red spotting only when i wiped.. could this just be implantation bleeding? or  should i be worried?