Is there a way to zoom the overworld map without a scroll wheel on my mouse? There's so much detail I'm missing without the ability to zoom. Thanks.

You're not missing any details on the default overworld map my friend. Zooming in is practically pointless.

I'm still astonished that you have a mouse without a scroll wheel on a pc that can run skyrim. Bootcamped Mac?

You will need a scrolling mouse in the menus when the columns grow longer. Get a better mouse.