I think the GP is possibly reacting to the word "metastatic" in ultrasound report. But the person reading the ultrasound would NOT necessarily have knowledge or even awareness of your complex HAE history - would just be reading the ultrasound in the usual way & reporting on typical and possible findings. But WE all know your body is not 'typical', and as you say you have not had any other indicators of cancer. So personally, I think it's important, although very very difficult, to not get wrapped up in that narrative until you have more certain studies done that DO take into consideration your complex and rare genetic condition. Very frightening in its possibilities, but it's also possible that cancer is not the end diagnosis. Just saying.
I'm truly hoping you can get some rest, breathe and find some peace until such time as the diagnosis is clarified. Sending light & love to you this night.