Your nails do sound like they have psoriasis. I also have nail psoriasis and PsA, and I've never had any skin plaques. It makes sense that you may have PsA, since it is often sero negative. Keep working with your rheumatologist!

I’m right where you are. Thought sero neg RA but after a big for me psoriasis break out, only on hairline, the thought psoriatic arthritis. I get psoriasis break outs maybe once a year, tiny spots. Had arthritis of some kind now for two years.

The nail issue is sometimes associated with pscorisis.

https://www.ldnresearchtrust.org/gil-us-shares-...

Listen to this interview...very encouraging.

https://www.ldnresearchtrust.org/what-is-ldn

Check out Low Dose Naltrexone at the above link. It has been shown to slow and halt the progression of auto-immune diseases because it boosts the immune system rather than suppressing it. It usually takes about 6 months to see results. I'm taking it religiously and seeing improvement after 5 months. There are zero side effects. All these biologics work by suppressing the immune system, which to me is sheer madness. Best wishes to you.