I was quite content with the way I played this game, I would play it nearly the same were I to play again. I still lost by 8,5 points, though. Did he simply play much better overall or did I make some big mistakes?

You could well be stronger than me, but here are my thoughts.

48: You have three weak groups and black has one, so this fight seems much better for black. I would be more inclined to try something like Q9 with the aim of forcing black to connect on the second line while connecting two of your groups.
70: My instinct would be to play Q13 first. It doesn't seem like black can do mmuch more than defend.
70+71: I think this kind of exchange is a good thing to look for if you're having trouble finding where you went wrong. You were forced to let the group you were attacking connect to safety in exchange for covering your own weakness. That's fine if it's the peaceful end to a profitable sequence, but for me it's always a red flag that I need to consider:

a) Did I profit from this fight?
b) (If no) Was I too weak to begin with or did I make a tactical error?
C) Was there a more profitable peaceful option?
D) (Depending on the answers to a, b and c) What were the moves that led to such a disadvantageous fight.

I can't always answer these questions, but they do often yeild useful insights. Edit: Also, these are the kinds of evalutaions you need to be able to make while playing, so I think it's worth practicing even if you don't end up with a satisfactory answer.

Edit2: I think you might find you get more comments if you post your level. Maybe other people are different, but I feel much more comfortable posting on a game if I know how the players' levels compare to my own.

A few comments.

_________________
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At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.