You can safely ignore average speed.
25 miles in under an hour as discussed above http://app.strava.com/rides/5696485#108609160
230 miles at 19.6 MPH http://app.strava.com/rides/3331484
Normal road hilly commute at 16 MPH http://app.strava.com/rides/7296360
I’m a crap roadie. I’m too fat and I’ m off the back when climbing on club runs. I managed to scrape 4 BC points in a 4th cat crit last year but there were only about 10 in the race! however, I’m an average time trialler. I finish top 10 in club events and top half of open events generally.
Ignore the averages, get out and ride with friends. Join the local club time trials for a laugh and measure your performance from there. Chain gangs are ace for developing speed and skills. Club runs are great for getting the miles and cake in. It’s all good. Stop worrying and start enjoying :)