Well if you're stuck with that board, then have at it. If you can try to trade down then go for something closer to 150cm. You will probably grow into that board though - you're only 13 with size 10 boots. Personally, I learned on a stiff 159 Salomon 450 when I was about 5'6" 140lb and I seriously think I wouldn't have improved so much if I hadn't conquered that board. Make the best with what you have - it might be good for you. Or if you can get another board, use that as your all mountain deck and get another soft, short board for your park fun.