Hla-b27 negative female here too. Diagnosed with spondyloarthropathy. The rheumy said time will tell if the diagnose evolves into PsA or AS (small peripherail joint involvement would suggest PsA, but the nail and skin evidence is not sufficient at the moment).
However, when dealing with GPs in the past when the inflammation occured only in my feet and hands, the negative Hla-b27 test was used as evidence that I can't possibly have a rheumatic condition. Go figure.