C.C.
Your addendum is very defensive! I, too, don't react well to people telling me what do to. But please take it in the spirit in which it is intended -- to help you because you're asking. Sometimes we don't like to hear the truth.
My husband and I also work full time and have three children, ages 14, 10 and 2. I have been so stressed out at times trying to keep up with everything. And like you, I was always so much more organized at work and was too exhausted to put more effort into it at home. But I realized in the end that it was my habits that had to change, in order to give my kids the help they needed. In the past year I have truly put forth the effort (not the failed attempts of the past, as you have experienced) and it is paying off.
I believe you are expecting too much independence of 6 and 8 year olds . . . they need your guidance to learn to add structure and routine, they don't just automatically know how to do it.
Trust me, I know about this one. My 14 year old is not organized at all but she is so intelligent! But her grades have suffered recently because she wasn't keeping track of assignments and then was lying to me about it. When she was younger it wasn't as much of an issue because there wasn't much homework and she was coasting off of her intellect -- and in hindsight I let her because it was easier on me. But it gets so much harder as they get older because there is so much more independent work expected to be done. So in recent months I have put a lot of energy (while working full time!) helping her put the necessary structure in place to keep on top of her assignments and be successful. It has paid off enormously. And she made a comment the other night that made me realize that she truly appreciates it, even if I was being a hard-nose about it all!
Yet my 10 year old is very organized and independent. Each week she is required to independently do 100 minutes of reading and 75 minutes of math, in addition to other homework assignments. She has learned to break her assignments down into small pieces each day, so that it is not overwhelming and by the end of the week everything is done. It is a skill a truly admire in her, and wish I was better at! She usually does her required reading before bed, although she prefers to do it independently vs. reading to me. But what is 20-40 minutes of your time before bed to sit with your daughters while they read aloud to you? It really doesn't require much effort on your part (except to help them when needed), and I have learned even that small amount of involvment pays dividends. Divide and conquer - you sit with one daughter and your husband with the other, then switch every other night.
I do not begrudge you looking for help because we all need it. But maybe your looking for help with the wrong things. Make the time to work with your children -- parental involvement is shown to have such a long term positive effect on a child's self-esteem and success. Your girls just aren't going to get that reading out loud to a stranger. One hour of your time each day to be a positive influence and role model in your childrens' lives -- does that really seem like too much?