Oh, and one thing. You say that you're spending time thinking through your buys, and that's good. I would also say it makes sense to, at the beginning of the game, look at the cards and sketch out your overall strategy. That way, regardless of whether you win or lose, you can think about 'did my strategy play out the way I thought it would' and 'was my plan good' - you'll spend the same amount of time thinking about buys, but a lot of it will be front-loaded.
Like, looking at this game, I can't really see what your plan was. Dominion isn't just a game of individual cards, individual buys. We can point to individual cards and say 'mine is bad here, lighthouse is bad here, peddler and grand market are good here' but it's probably makes more sense to talk about the strategy as a whole, because typically cards are good or bad because they help or hinder the overall strategy.
Here - your opponent had a well-defined strategy. They were going for a cantrip engine - a deck full of Grand Markets and Peddlers, aiming to be able to cycle lots of them for lots of cash and buys. They immediately got started with a Salvager to trash things; the early silver was trashed on turn 6. They got just one gold, and no other treasures, getting just one lighthouse and cartographers instead of silvers. This let them get to Grand Markets and then to lots of Peddlers and finally to Provinces. It was a good strategy, probably the best one around.
You got multiple golds and silvers, so your strategy was primarily Big Money. It was supported by one Mine, one Cartographer, two Peddlers, and three Lighthouses. I don't really see how those cards go together, and I'm not really sure what critique to say since I'm not sure why you bought them the way you did. Those are all good cards - but not necessarily good the way you used them.