Relentless attack on Castled King. Losing games despite playing well.

You always want your moves to do as many things as possible.

Here is the key to winning a game like that, the checkmate was not forced, so study on how to defend against the attack, and if you can survive, you come out with an advantage. So just study every move you opponent makes before you end up in that position.

I also have to say that I LOVE you opening style, you use all the space gaining and developmental technics that most players at your rating don't usually play. Keep plugging away.

Chess is essentially this: from basically an equal starting position, each side attempts to create one or more small temporary advantages with the goal of eventually turning the small advantages into a permanent, winning advantage. You saw that in your game where at different time either black or white was better. Eventually the game ended when a small advantage of a local concentration of enemy pieces overwhelmed the kings defense. So aside from improving on tactics (not blundering pieces, walking into a checkmate) ask what were the small advantages? And how do the small advantages become permanent, winning advantages?  Example if you win a piece you have a material advantage, so the idea would be to trade all the other pieces off the board to make your piece advantage permanent. Another example if your opponent attacks your kingside, then counterattack in the center which can lead to you controlling the center and having a space advantage. Another example if you have a superior pawn structure then trade everything and get to a winning endgame. I recommend books by Yasser Seriwan to help get some ideas. Generally your game will be dictated by tactics at lower levels but you are right to start having plans and a style of play you prefer.  Just sometimes you wind up dealing with your opponent instead of your opponent dealing with you.