We had a similar problem
We saw much the same thing when we started out in our C22. It has a lower hull speed (by 1-2 knots) than bigger boats, so this may be part of it. You won't overcome that factor. I also tried to emulate the sail trim of those bigger boats when we were headed in the same direction, assuming that they were more experienced at it. In this respect you might try a larger sail, such as a cruising spinnaker. I eventually noticed that some of these faster, bigger boats were spouting water out of their stern, i.e., they were motor sailing, which accounted for their speed. Finally, I tried more often to set my course to take advantage of the current when I could, and stop fighting it.