Editing, or the pitfalls of woodwork

So I've been editing "Teaching Tori" for a while now. It feels like months. No, actually, it feels like years. Is this normal for a first novel?
I sent my first chapter to an editor in November and got valuable feedback which allowed me to make improvements which I could not have spotted without her help.
Now I'm happy with my first chapter. It's like a wooden sculpture with its fine sanding completed, just waiting for a finishing gloss (probably more likely to be oil for wood, but that doesn't seem to fit my metaphor for this purpose).
After working hard on chapter one and achieving this smoothness, the subsequent chapters feel like a rough cut - a block of wood with edges and odd angles that don't seem to be quite right, yet.
Every day I'm cutting a little bit off here, sanding some more over there, and wondering in the process whether I should start all over, or whether I cut off too much.
This bit-by-bit editing is very time-consuming and inefficient. I definitely need an editing plan for the upcoming school holidays to get this block of wood into a more aesthetic state, worthy to be sent to an editor for ideas on further polishing.
There must be a more efficient way to edit than chopping and sanding. Have you found it? And are you willing to share it with me?