We just want an amicable divorce. We agree about everything. Why would I need a lawyer?

Your story makes no sense. If you agree about everything, why do you need a divorce? There is hurt and distrust lurking under every divorce. If you could trust each other absolutely, you would not be divorcing. Spouses naturally want to take advice from each other and rely on each other. But once the fundamental glue in your relationship has dissolved, you can't trust your spouse's advice. You need someone neutral and knowledgeable, whose advice you can rely on. Maybe that is your mother; or it might be a lawyer.