I hoping for the 170s next week too. We can do it!! But...... if that scale isn't nice tomorrow don't let it get you discouraged. Sometimes I feel like my body (or the scale) knows when I'm about to lose more of those "important" pounds and it just makes me wait for it. But if it's not there tomorrow it will be very soon. I just try to be thankful for where I am now, because I NEVER thought I could make it this far.
2.5 pounds a week is totally doable and safe. That sounds like a good goal! Best of luck to you!