Ride, ride, ride! And keep riding with people faster than you are. Among other things. 17 in the wind isn't that bad, by the way (says someone who hasn't made it up to a 17 average yet this season). Uphill, downhill, flat, steep, gradual, etc - it all makes a difference. Were you drafting? That makes a huge difference in keeping up with a group.

There is no "good speed" vs "bad speed". It's all about the individual, the terrain, the bike, the weather,......... I think ya done good!