First thing: thank you all for the good advice!
Yes, my learning might help others too. On the one hand, I hate strugling with my roll this hard. On the other hand, if I've had lots of problems, I'll recognise them sooner when teaching other people (hear me, I'm not even having a reliable roll and I'm talking about teaching others

I should write it down somewhere. Although most of the focus points are mentioned in the dvd's by Kent Ford, Bob Foote and all the books. You just have to realise what exactly is your problem.
@ Wetnobby:
You're probably right. I do know by now how to do a good, effortless roll -though there is still some room for improvement-. But now I have to cement it in my system, so that I always do the good thing.
The next thing is to keep my eyes closed and improve my setup there.
The rushing thing was actually true for me. I rushed, afraid of getting out of air. Now I learned to wait, get my "second air" and then roll up. Now I tend to hang in my boat upside down for a couple seconds and then start my setup. I probably do a similar thing with my eyes closed.
Wasting the brace I don't do anymore, if I do a good timing and remember to push the T-grip down. I used to have painfull shoulders and ellbows after a pool session. This week, I haven't had any. I hardly use the low brace now.
Anyway, I have all winter to work on my roll. Hopefully I'm able to roll once in a while on the river by Easter, when I start my non-belgian whitewater river season.
Next weeks pool session will be a great test: do I still know how to do it correctly?