I have problems with Chrome too and it's very annoying. I find clearing the browsing data solves the problem. Go to 'Tools' then 'clear browsing data'.
I'm a size 6 and ordered a 6. At first I was worried they would be too small when I put them on but after wearing them for an hour or two the fur bedded in and they were really comfy. So I'd say if you are a full size, order your normal size.