I am 37, one child, not on birth control pill. I didn't get my period for the second month now, took 4 HPT's, all negative. One blood pregnancy test at the hospital - negative as well. Today I got an Ultrasound and the technician said that there is "definitely something going on", and he said something about the endometrium was 1,5 cm. He couldn't confirm that I was pregnant but told me to come back in two weeks, if I wouldn't get my period by then. What could be the cause of all that? I don't really feel pregnant except that I am very tired.