There's always the possibility that the rage and anger coming out now are actually you dealing with past issues that may be in the way of your effectively using the LOA. Some of us reach this place with more baggage than others and I feel that could have something to do with why some go through a "purification" process. It could be that we inadvertently 'intend' these changes within ourselves to help put us on the path to happiness.
As far as being upset about discovering that I could have done better if I had the information I have now, I would say it's more of a regret than anger and the knowledge that I am responsible gives hope, it removes me from the role of victim. Now I know that I am not waiting on someone else to give me a break, I'm waiting on me to give me a break
, big difference.