Yes to the above, but first, more ground work. I know, everyone says this, dont' they. But a hrose that throws a hissy fit in the round pen when asked to move forward, really move forward, and do it Now!, this horse needs you to work through that in the round pen first.
Let her have her fit, at first. She buck her little heart out in the round pen, you will NOT be dissuaded by it. LIke a parent that will not let a tantrumming child get their way, you will not forget that you asked for forward, and by God, go forward. So, dont' let her bucking distract you. Just keep asking for forward and dont' accept anything that isn't honest. Don't accept her pinning her ears , don't accept her bucking or kicking out at you. Keep asking MORE! Until she leaps forward at a good cante when you ask with the whip (free lunging in the round pen) and get her so happy to go forward that you can do it with your body language. Once you get that. STOP totally for the day.
YOu need to get her to bust throught this logjam. I bet she'll be far more willing to move when you say so the next time you either roud pen or ride her.