Stressing about finances - how much to spend on nursery?

Don't get me wrong. My husband and I are comfortable. We own our (tiny) home, live a happy life, and feel prepared for the financial obligations that come with raising a child.
Yet I'm so nervous. We're saving as much money as possible, because I'd like to extend my maternity leave (i.e. I'll be out unpaid for a bit), and we'd like to move into a larger home shortly after baby is born. Operative word being "like" - these things are not necessities but our goals, I fully realize that.
But certain things are seriously stressing me out. For one, I am in a wedding that is costing much more than I anticipated. We're also in the process of getting our nursery started, which costs money too, of course! And I just can't stop thinking about money. 
For those of you who've already started your nurseries, how much did you spend? Where did you save vs. where did you splurge? What things were worth the money, or what purchases did you regret? I really want to start getting ourselves ready for our baby but I see my nursery budget dwindling each time I get another "bridesmaid bill" for this wedding.