+1 on getting a teacher.
But since we're similar body sizes I'll throw my 2 cents in (you'll have to do the conversion from Euros).
IMHO the back right corner of the bass should sit in between your left hip bone and your belt buckle, with the bass at an angle of about 10 o'clock (straight ahead is 12). Then you have to find where it balances by moving the neck forward until the weight is too much in your fingers and backwards until you're holding it too much in your hand/thumb. The balance point is somewhere in between. The place you want to find is where the bass is just behind the balance point, resting slightly on your thumb but not with any real weight. Then you can bend at the hips or knees to allow the bass to come in to you more, especially to allow the neck closer to your head so your left wrist isn't too bent.
How's that for wordy?

Get a teacher!