How likely is it that 2 rounds of bloodwork and 3 ultrasounds within a year missed cirrhosis of the liver?

Unlikely. It would be very unlikely. Other tests that could be done to confirm are MRI, CT scan or liver biopsy. You could consult a hepatologist for evaluation.
Likely. cirrhosis can often be 'compensated' meaning no issues with bloodwork. USG is notoriously poor at picking up cirrhosis - again only good at decompensated stages, when there is an enlarged spleen and perhaps ascites. the true diagnosis is made by biopsy or now fibroscan.