Being autoantibody negative and having some endogenous insulin production certainly does not rule out Type 1 diabetes. All factors being equal, if you were a child a pediatric endo would almost certainly diagnose you has having Type 1 diabetes (or look for clues for MODY). Regarding autoantibodies, more and more have been discovered over time (and HLA genes or c-reactive protein also gives clues to autoimmune diabetes). Regarding insulin production, The Type 1 Diabetes Sourcebook (ADA/JDRF 2013) says, "It is often unappreciated that many individuals with T1D will have significant amounts of C-peptide, representing residual beta cell function. The standard teaching that T1D is defined as complete absence of beta cells is inaccurate and is a disservice to both patients and providers. Among 411 participants in the Joslin Medalists study (those with T1D greater than or equal to 50 years), 67.4% still had detectable C-peptide." Pages 26 and 27.