I've just gone from a 10 gauge to an 8 gauge. I've been wanting to go to a 6 gauge, but I keep hearing that from an 8 to a 6 is a full mm and the stretches tend to be more difficult. Has anyone else done this or know of someone that has? Any advice would be greatly appreciated.

I have had my nipples stretched up to 3.2mm. Nipples are very sensitive, they are erectile tissue and thus behave differently to 'normal' tissue. Personally I waited a year to stretch my nipples to 3.2mm (from 2.4mm) and did it in one go. I do not recommend stretching one size up in one go, go up in half sizes. Way easier and less stressful on your piercing and body.

As far as I know anatometal go up in small increments so give them a whirl and see what happens. Hope this helps :)

Taping is a good way to stretch for some people. There are many topics on the subject if you browse around using the search function.

 just don't be stupid about taping a nip.

I should have known someone was going to post that.  I was eating too...

 Anyway just make sure you listen to your body.  You'll know what's normal for your body and what's not.