(Your English is actually quite good, don't worry about it.)
This question is actually quite common. Here's another thread where it was also discussed, with some links that might be helpful:
http://forums.omnigroup.com/showthread.php?t=23281
Is OmniFocus too much for you? Would Reminders be enough? From your list, I would guess you want something more than Reminders. You could try it for a few weeks, though, and see.
Anyone else have thoughts?