Still not used to my board. Can only use Burton LTR.

Did my lessons with a Burton LTR rental and also used the rental for a day on the mountain and felt confident. Then I bought an old used Elan Aurora 2008 board and even after trying it 7+ times, I still feel significantly worse on it than on the Burton LTR. I know it takes time to get used to another board but it’s been a whole season now. One example is, I am struggling to control my turns. When I turn, I keep turning my whole board horizontal and accidentally stopping, when I mean to just turn it slightly. It’s probably a skill issue but I didn’t have this issue with the rental boards. Is this solely a skill issue or would getting a different board help me? Any recs for a board?

I would buy the Burton LTR but was told I would grow out of it. Also don’t want to get it mixed up with the rentals. If it matters, I am 5’4”, 110 lbs.