Declining results and technique?

Sorry if this is overlong, but I am discouraged, and need some encouragement. Since getting back in to swimming this past summer at the age of 54, I have been in 3 events. My main stroke is the 50 breaststroke. This summer I swam a 39.42 for 50 meters in a non-sanctioned event (they take the middle time of 3 hand-held timers). I was delighted, because 36 years earlier at 18 my best time was about 36 seconds (and that was a relay split as we only had 100s back then), so I figured for a guy my age, that time (the 39+) was pretty good. I had only trained about 7 weeks. I had a trainer for dry land workouts, but really no swim coaching at all. In my second meet, and my first sanctioned one, I did 40.71 (also for 50 meters) in October. Today, I did a 38.0 for 50 yards, which translated to about 42 and change. When I did the 39.4, I swam 6 events, for a total of 225 meters (there were some 25s). Today I swam only 1. I have also gone from 220 pounds down to about 203 (I am still overweight with about 19% body fat). It seems that things should point to my getting faster, not slower. Two things have changed...I am logging MORE time in the water, but have reduced my dry land training to almost zero...just doing 100-200 pushups a few times a week, but no work with a personal trainer. Secondly, I am trying to use the new breaststroke technique, introducing the dolphin kick, focusing on getting more streamlined and submerging my whole body on the extension, tucking my head to lower water resistance, and lifting my head out of the water less on the outsweep. I am guessing the learning the new methods is taking some time...it is not automatic yet...I still have to think about it. I guess I answered my own question to some extent, but would like to know if folks think I should just revert to my old flat style or keep trying to perfect the new. I also welcome any other ideas about training, day of race prep, and the like. I feel great in practice, and some of the lifeguards who are swimmers say I look fast, but on race day, I seem to psyche myself out and forget to concentrate on what I am doing.