I am very glad that your first sail in #362 went so well. I have been waiting to hear the story of your first time out ever since we first began corresponding about your boat, and about all of the work that you have had to do to rebuild her. It is good to know that a sister ship of my #363 is being cared for and sailing.
A few questions, if I may.
When you reefed the clew, did you perchance reef with the outhaul, the line that you would normally tension the foot of the unreefed sail? That would account for the sail being pulled straight back.
Did you pull the reefing lines in the reef points between the tack and clew tight? If so, you shouldn't have. All of the load should be on the tack and clew reefing grommets (cringles), which are reinforced with several layers of sailcloth. The intermediate points are really just for looks in a mainsail as small as the P-14's.
The P-14/15 sails very well on main alone, as you've found. In some respects, taking in the jib, or not setting it, is a good first reef.
The first time that I sailed my Potter (on our little reservoir here in central Indiana) the wind was blowing quite hard, and I almost didn't go out. I was very conscious of the boat's small size, and the fact that almost no one was out. I had only the small mainsail up, and had it reefed. Once I got away from the dock and out into the lake I realized that the boat was doing fine, and that it was only really sailing well in the puffs. I should have shaken the reef out as you did, but I was lazy.
Again, I'm glad to hear that your first sail went so well.
Regards
Tom