Thanks all you guys, it's cool that weak players like myself also get help from you!
My goal at this moment is becoming 1600/1700 so I could play some games here at the local club and sort of have a shot. All your advice I will take with me.
- play a opening I know better, especially against stronger opponents
- try to trade more, especially with stronger player,
- defend the centre-fields better (albeit I have to say that since I knew I would lose this one, I also took a not so known opening, in the hope he wouldn't be very efficient at either (a wrong tactic as I have learned now)
- check better for blunders before moving
- better protect my pieces
It all seems so simple when I put it like that, but I'm sure it will be a challenge in itself to achieve these goals :)

By the way, I thought you played a good game. I am just suggesting that such an aggressive approach was destined to fail against a much stronger opponent.