First of all, I reeeeeaaaaalllly like to plan too - it's a hobby ;) - so if that soothes you and makes you feel better to have a long term plan in place that you endlessly tweak, then go for it and knock your socks off with it!
But it kind of sounds from your post like having a long term plan in place is stressing you out, not soothing you. It's really ok not to know what curriculum you'll be using several years down the road!!! So many things will change over time ... your family size, your understanding of your kids and their learning styles, your own teaching style and abilities ... it's impossible to know what will work out over the long haul. So do your research and make tentative long-range plans, but don't stress out about finding the perfect curriculum for when the kids are XXXXX ages. Find the curriculum that works for them right now, and go from there.
It sounds like you're off to a great start with your first 2 children. It's so easy to combine at that age, and doing lots and lots of read alouds is really your most important priority. Unless your kids have significant learning challenges, in my opinion it's best to go with a curriculum that YOU enjoy most and can implement on a consistent basis.
The independence thing you do need to be somewhat purposeful about teaching and encouraging, but it really does come along with increased maturity as the children grow. I remember not really believing that when mine were all little and needing me so much, but trust me it really does happen as they grow and mature. In 5 years from now, you won't believe what all they can do on their own. :)
Good luck and God bless!