How long it takes you to solve the puzzle matters a lot. That 1450 puzzle you beat would have gotten you more points if you solved it faster.
Puzzle Math
Just keep doing puzzles as fast and as best as you can. It's not like you'll stop doing puzzles because of that 1375 or 1450 puzzle. Let the algorithm run its course and simply try to reach higher.

Just looked and your puzzle rating is 1684. So, theoretically, you should be able to solve a lower rated puzzle. Solving a 1450 puzzle is a minor thing, considering your rating. Failing to solve a 1375 puzzle is more significant, because it's 300 points below your rating and you (supposedly) should be able to solve it. HTH
I'm confused about how the ratings work on puzzles. If I lose to a puzzle that is rated 1375, I lose 15 points. If I beat a puzzle rated 1450, I get 5 points. You lose a lot more points when you fail than you gain when you succeed. Is this just the nature of ELO or whatever? It makes no sense to me.
M.