What Causes Symptoms Of Pregnancy But Negative Pregnancy Test Result?

I would like to ask for your help. My husband is stressing me out.
I have irregular menses. I have short and long cycles.
my first day of my last period was nov. 17. we took a home preg test last dec 23 because the longest cycle that I recorded is 37 days. It turned out negative.
Even if it turned out negative I show signs like lower abdomen cramping, headaches nausea, back aches, and sometimes my breasts are cramping too.
It's already dec 28, I still don't have my period.
we are speculating on weather it is PCOS or ectopic pregancy. well I have been observing and I don't manifest any signs of those. I would really want to hear a response to this. thank you.