I know how you feel too! Natalie didnt' engage until a couple of days before I went into labour, and she was a week overdue. I was really depressed on her due date because she didn't look anywhere near wanting to move.
Everyone's said it, but try to relax (I know its hard). When you sit down, try to do it on a dining chair that you can straddle and lean forward so you're resting your arms on the back rest IYKWIM - I was told that that helps to get bubs into a good position. (Plus, I found it really comfy - even during labour )
All the best. Not long to go now.