BTW, I'm not an expert skater.
But as to what causes a bunny ear shape, it means that both the toepick, and a point further back, slide as you turn. I don't think the toepick should slide in 3-turns. In principle, if you put more weight on the toepick during the turn, it won't slide, but I don't know if that is the issue for you. For example, alignment and weighting points can affect them too, as well as what the prior poster said, and maybe there are other things. For me, I like to have more weight on the inside of the blade when doing inside 3 turns, and to have "deep edges" - i.e., to have the body and blade lean to the inside, while pushing the blade sideways against the edge. And during the turn itself I like to push down hard.
But a coach could do a much better job than me of figuring out what is happening.
BTW, do the two sides of the bottoms of your feet (especially up front, but also everywhere) feel like they have equal pressure on them while gliding on the flats (on both edges)? If the inside has less pressure on them than the outside, that might make inside 3 turns harder to do well. That can be fixed with blade offsets and/or insole modifications.