How do you stop yourself going totally insane???
LOL, I completely commiserate. Of course I have days where I really struggle, but the going insane part I find can be avoided if you remind yourself "she is only 2". And try really hard to marvel at how thoroughly wonderful it is that she is wanting to dress herself when there are older kids whose parents are ripping their hair out because their school-aged children are still unable to promptly dress themselves. Be proud that she is TT at all because some kids (like mine! LOL!) don't catch on to that AT ALL until much, much later.

Please don't think I am criticising your frustration - believe me I TOTALLY get it. DH and I were lamenting about my 4yo DD's ability to whine about everything - and we were on holiday and she was having a lovely time! We had to keep reminding each other that she was overtired and as a preschooler she just didn't know how to deal with her feelings in a sociable way. "She's only 4..." was our mantra all weekend long
Your DD sounds like a really bright little spark and focussing on the positives will stop you from going insane, even if it won't prevent your frustration at her behaviour