I know exactly how you feel, i just had Josh 3 months ago and i was 1 week overdue. Apparently it is the hormones in your body that makes you feel this way so you forget about the birthing process, as some are anxious about it, and just focus on getting it over with.
In no time your little one will be here so enjoy your rest. My skin use to feel so itchy by the end and my ribs use to ache.... trust me we have reason to feel tired and grumpy.... its are hard thing to make a little human being. You are doing great *hugs* and remember if you feel tired just rest! Take care