Did those tests include at least a few antibody tests plus a c-peptide test? I recommend that you do a site search for posts by @Melitta who has written extensively on the topic of T1Ds misdiagnosed as T2Ds. That may not be your situation but it’s common enough that you should consider it.
I admire your proactive stance regarding your impaired glucose metabolism right from the start. I think you’ve likely prevented a lot of damage to your health. Your strategic use of walking to knock down trending post-meal glucose hypers is effective.
You may benefit from adding a long-acting insulin to your regimen. You don’t mention a doctor in your post; I assume that you are seeing someone regularly to monitor your status.
Good luck.