My apologies,
I followed the instructions you gave above, but those didn’t help so I deactivated and deleted both plugins (styles and styles:twenty twelve). I re-downloaded both and activated them one at a time.
Again following the instructions above for Styles, that method seemed to work. Then I activated Styles:twenty twelve and the site got small again. I deactivated styles:twenty twelve and the site was still small, so i followed the instructions above but this time it didn’t work. The site stayed small
Also it wasn’t that I was curious if I needed a child theme, more so how well the plugin works with one, but now that I think about it, something in styles (seems to) override the custom size in my child theme.
Thanks