Its VERY easy to overpack. You will, sooner or later, have to resist the temptation to take everything YOU THINK you'll need. Much better to get rid of it now, and pick up something when YOU DO need it.
Don't think you have to fill every compartment, you'll be overweight for sure.
Jim-Linda had it right to begin with -- pack it and weigh it. I guarantee you, you'll start with too much. Make it a six month commitment to weed. If you haven't used it in 6 months, the odds of you needing it will be slim. After 12 months, you'll know for sure.
Best of luck to you.