I've been experimenting with Lists and Circles to see how they help. (But you and @cowgirlcoder haven't responded to a Circle msg, so don't think it works like I thought, e.g., a contact list.)
The issue is the balance between stagnating with a set of people versus dynamic exposure to a wider set.
A circle is a contact list on M. A message is only sent to those in the circle. "You" is you, Soupy, and TonyK.
Could you check your DMs? I don't think that is the problem because I got a response to a DM from someone else in my timeline.