How can I know if I'm making progress?

By the amount of peace in your awareness. Of course, the Peace that has no opposite belongs to a different realm than the one we believe we're in. Here, peace comes and goes, and has varying definitions, degrees, and causes.

The ego's view of peace is something along the lines of "can't complain." When life is going along reasonably well, we tell ourselves that we are peaceful. But think about it. Even when things are going well, you're not totally at peace because you're worrying that it won't last. (And you're right!) When looking through the lens of ego, we tend to define peace as anything that props up our sense of self--especially in the perceptions of other people. That's not the kind of peace I'm talking about.

I'm talking about deep, inner peace. Peace that is irrational. Peace that is there for no apparent reason. When you look at the events of your life and see many reasons to worry, attack, be defensive, be angry, be upset. . . you see all these problems, and yet what you FEEL is Peace... THAT's what I'm talking about! A sense of Peace that doesn't even seem to come from anything going on in your life.

The more often you are aware of THAT kind of Peace, the more progress you are making in your spiritual path.