Frustrated 😞

Hi guys, I'm a little frustrated this morning and feeling down. I would be 4 weeks exactly today if I conceived. Yesterday I was supposed to get my AF but it never came and hasn't come this morning. I've had cramping on and off since a day after my husband and I had unprotected sex. I really think I'm pregnant because so of the symptoms I've experienced. The only thing that worries me is I don't have any breast discomfort. I took a clear blue digital test this morning and it said not pregnant. Could my hcg levels just be to low to show. Feeling down about it 😞