Hi, and welcome
A child may HAVE ADHD, but it is not what they ARE. Never tell a child they ARE ADHD.
These statements jumped out at me from your post:
"Taking things away do nothing other than hurt her feelings, which leads to anger and more
Cindy, mom to
Chris, 12/96, ADHD and sensory issues
and Meagan, 10/02
Feel free to read the parenting books for ADHD, they actually include (well, the good ones) a bunch of "how to handle your child" advice that's perfectly applicable to every kid.
I don't think timeout-sitting-still *ever* worked well with my kids, either the ADHDer or the still-not-got-a-diagnosis-and-he's-nearly-9-so-maybe-I'm-safe one.
Doing the 1-2-3 Magic thing worked *great* for us. I found I had to state the consequence by #2 as we got into it. It also makes staying calm much easier on everyone; you simply don't get as frustrated. And now that they are 12&9, I can quell 'em by just holding up fingers counting--not needed often, but a really fast way to make my point in public!
POSITIVE discipline also works really well--better than negative, I'd say--on lots of kids. So, sticker charts, that kind of thing. I know you say you haven't found her currency, but I'd bet that you know some things she wouldn't mind earning. The secret there is making the thing be doable, and working on very specific things, one or two at a time. Don't make the system to impossible to understand & upkeep! If it's a baby-sister thing, something like a sticker for NOT doing whatever the things are she's doing wrong every X time period. I found frequent rewards at first, tapering off as the kid got better at whatever it was. This stuff is best discussed between you & spouse first.
Constant movement isn't necessarily ADHD, it can be sensory as well/instead. The nail biting could be too. Either way, you might make sure she has plenty of time to be really, really active--like, before you go somewhere she needs to be quiet, you let her run like crazy, or swing, or whatever. Possibly worth looking at the sensory stuff if you haven't.
I'd also say--with regards to your GF--you may simply have an active girl, which is, I suppose, rarer than an active boy, but I've seen plenty in my kids' KG classes & such-like. Lots of nice quiet little girls, too, and the active ones do stand out next to them, but not so much next to the boys. If I'm making any sense?
I think you got some really good advice here!
I also love "1 2 3 Magic".
I didn't read the responses, so I apologize if this is a repeat.
Oh oh, I also wanted to say this.
My son was dx with ADHD at 4 years old (he JUST turned four at that time).
So while he even admitted he wanted to wait until he was 6, he dx'ed him anyways.
A> because it was obvious that SOMETHING was going on
B> because I knew he would not get 'service' without a dx
C> probably because of the family history
D> because I had been actively seeking answers about him since 10 months old
I know this is not the norm.