Your current rheumy doesn't sound like she knows what she's talking about. You can definitely have a negative ANA and have a connective tissue disease. There are many AI diseases that don't have a positive ANA. I don't have a positive ANA, but I am positive for RF. the positive RNP antibodies you referred to, I believe, are associated with MCTD. My mother had a negative ANA, but was also eventually positive for those same antibodies. She had MCTD. I would look for another opinion, if I were you.
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Lupus
Current Meds: Enbrel, Methotrexate, nexium, tramadol, nasonex, Nifedipine, Folic Acid, Tylenol PM