For the moment, you bit off a bit more than you can chew. New riders make out the best on shorter, flexible boards. Such boards are more maneuverable and more forgiving than longer, stiffer rides. At your weight, you would be in the suggested weight ranges for some decks as short as 150cm. This is not to say you have the "wrong" board, it just means your a little behind the 8-ball for the time being. Keep taking lessons. Perhaps even a private one. They can really help move things along when you are still at the start of the learning curve. Also, steeper trails are not easy. They take a lot of time and a lot of experience to nail down. Keep with it, and you'll soon be tapping into what that deck really has to offer.
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"Up, up, my people, let smoke and flame be our sign!"
-The White Rose Society