Gpercy - the future next actions you have identified for your project go in your project support materials - I am assuming they have pre-requisites. However, remember one thing (and I think this is what David is getting at): Projects develop, they do not often come together in your head in full-form. Plans often do not remain intact once you start implementing them.
When you go back to your project support materials to review, you are not just looking for one of the next actions you thought of last week, you are also seeing if those next actions still apply, or if new ones need to be added etc. A next action is, as mentioned, a "stake in the ground." If you are "in context," you can use it to move your project forward during "weird time" (David's word) - those little slots of time that normally get wasted in the busy-ness of the day. And if you are in "project mode" - ie. you have a block of time set aside on your calendar to really crank through some project related stuff - you will remember easily where to pick up again and so get "back into the flow" much more quickly.
Also, for Erin - the base of knowledge and experience that is crucial for developing your "intuition" is your Weekly Review. The WR is not a time to do next actions, or even to clear out your inbox. Try to have that done ahead of time. It is a time to review - to literally go through your items/projects/calendar and overview your life as it has occurred over the past few weeks and as you would like it to end up over the next few weeks/month or so, and plan accordingly. You will find nothing allows you to feel that sense of control you are missing like the WR. And, in your early stages of implementing GTD, don't be afraid to make it a semi-weekly review as needed, just try to avoid the bi-weekly or monthly version