Suggest Remedy For Delayed Periods

I think I might be pregnant because as of today I am 14-16 days late of my period. I took 6hpts all negative. 2 blood tests negative but had an ultrasound with a thickened endo-something (I m sorry) haha but she said there s no way I m pregnant. what s going on? could I very well still be? I d only be 4 weeks and a few days preg.