I agree with what everyone else is saying. The Weekly Review is not the time for detailed project planning. I use it for project review and review of higher elevations.
With that said, everything takes longer in the initial stages of GTD. You don't have a system up and running, you still have to discover the methods that work for you, you still have to bring your habits in line with GTD. The good news is that because of that you're keeping a close eye on your system on a daily basis. Especially in this case, where you seem to have a large backlog of planning to do, things probably won't get too horribly out of control if you spend your general review time focusing on some of that backlog.
Put another way, the Weekly Review is most useful once you have a system to review. Right now, you don't.