You are not alone. The experiences you identified are common among veteran teachers. The ability to interject at the 'right' time is an art. Getting the adult learners to generate the conversation in the desired direction is much more difficult than just dumping the curriculum content in to the conversation. Nevertheless, as it occurs, you will see the learning to be much more robust for the students. Think about questions and questioning techniques for your classes that can elicit guided, (but open ended) answers that beg additional input from other class members. It's fun to watch the conversation unfold when it happens. Then your input is mostly encouragement and confirmations from that point on in the thread.