First off, she's quite a cutie! And sounds like she has some really good basics so far.
Yep, if you can tie her up somewhere, just let her fuss it out, and trust me, eventually they will just hang out and take a nap. Last year I left Nova for 30+ minutes tied up and after a bit of bored fussing, would give up and stand. (This was easier because I could go in the house and watch him, and he couldn't see me.)
In the roundpen (and yeah, like QHAA said, go easy there because of her baby joints) have you worked on getting her to whoa, walk, trot, (sometimes) canter on cue? Nova was only lunged about 5 times last year, but he learned the basics - and this year I will be expanding on those and expecting quicker/more precise responses.
When you're leading her around the arena, don't be afraid to ask her to stop, back up, turn towards you and away from you. And you can start working on having her do turns on the forehand and haunches, just remember to start small and only ask for a step or two at a time. Since you have access to ground poles, have fun with them. Set them up in a big L shape and have her walk then back through it. Put a tarp on the ground, then the poles to hold it in place, and have her walk across that. Do all sorts of obstacles - like you would in an in-hand trail class. Also by doing all this, maybe you can haul her to a show or two this summer - those are really good experiences for the young ones. Do halter, showmanship, or in-hand trail if the show has it.
If you have someone knowledgeable about ground-driving (long-lining) who can help you get her started and going on that, go for it. Perhaps start with a halter or sidepull, then maybe graduate to a bridle if she's going fantastic. This way you can work on her steering but without lots of stress on her joints. Doing this would also be a HUGE step for her undersaddle career - I wish I'd done this with Nova last year.
Later this year, if things are going well, put the saddle on, and lunge her for a bit, let things flop around and hang off of it, so she gets used to all that. If she's mature enough and doing well with the saddle, maybe you can get on her. If you have help, of course! Last year I sat on Nova probably 3 times, just getting up, letting him get used to me, and having my helper lead me around for a minute or two, and then dismounting. He did really well, and was unconcerned, and I think this year when I really start him he won't be concerned about that part. (Now I just have to get him to understand the rest of riding, and I might be okay!)