Could High Anti-U1 RNP with Negative ANA be MCTD?

I've had years of stiffness, persistent back pain (no slipped discs, etc., ruled out with imaging), and fatigue. It was so severe in 2018 that after months of PT, I was desperate enough to try a chiropractor who eventually referred me to his colleague, a physiatrist. He ran labs which showed elevated CRP, a RF of 45 and a Creatine Kinase of 356.

He referred me to a rheumatologist. She ran her own tests and at first, I was diagnosed with Ankalosing Spondylitis due to the back pain (negative for HLAB27). Then another rheumatologist diagnosed RA of the hips and spine. Then came a Spondyloarthropathy diagnosis due to enthesitis seen on imaging. And over time I developed telangiectasia on both cheeks with a V-shaped rash on my chest (dermatologist declined to do a biopsy as he didn't think he'd get much info back).

I have trialed various biologic drugs over time while on Methotrexate and low-dose Naltrexone as well but have never been able to get off Medrol completely, without worsening of symptoms. Labs have been done each time that show inflammatory markers increase each time I stop taking the steroid, despite the biologic and the MTX. I started Cosentyx by infusion and waited six months, and again tried a slow taper off the Medrol so that I could take a cortisol test to ensure that the increased pain and fatigue wasn't also related to adrenal insufficiency caused by the long-term steroid use (at least we now know that my adrenals are working!). Within 48 hours of taking the last Medrol dose, I became unable to get up on my own from a chair or bed, and I couldn't walk as I couldn't pick up my feet and both arms developed a tremor.

Some of my results are back from the period that I was fully off Medrol. Compared to the same tests done in December on Medrol - CRP increased x3, ESR increased x 6, Platelets and liver counts up, which all indicate increased inflammation. Today, I see that my Anti-U1 RNP is back and high - but my ANA is negative (back in September it was positive and speckled), which I don't understand.

The one thing I didn't mention that never seemed to fit in anywhere was that I had bouts of Trigeminal Neuralgia that preceded all the autoimmune stuff some 20 years ago.

When I look up what a positive Anti-U1 RNP indicates, it seems to be primarily associated with SLE and MCTD. I don't think I have SLE, but my symptoms might align with MCTD because of the muscle weakness. Trigeminal Neuralgia can apparently be one of the initial central nervous system manifestations of MCTD.

Question: is it possible to have MCTD if you have a positive result on Anti-U1 RNP but have a negative ANA? I am tired of living with "Overlap Syndrome" and hoping a new diagnosis opens different treatment options so I can get off Medrol as I need a colon resection and if I have to do it on Medrol, I'll need an ileostomy with it and I most definitely don't want that 🙁

Thank you in advance.