They have been mostly regional close to my Med school. I had a chair letter that was written by a PD affiliated with my school, the rest were just preceptor letters from 3rd year. I don't think your letters are the problem. It might just be that your app hasn't been seen by some programs, and maybe some low tier places are screening you out with such a high step 2 and decently high step 1, I am actually kinda worried about it too although my scores aren't as high as yours(step 2 wise), these low tier places that have many DO's and even some IMG's might look at our app and think we are prbly a back up for them, but the very top tier places are out for us cause of DO, we just need to bank on those mid tier and low tiers to come through, I think sending an LOI after this week will help a lot, and you should hear from those places hopefully (just my 2 cents though so who knows)