I'm freaking out about my snowboard now that its time to put up or shutup!?

I bought my first snowboard over the summer and have been dying to use it. I ended up getting a really good deal on a Ride 165cm Fleetwood (All Mountain - Wide). All summer its been there and the closer it gets to my first day on the mountain the more worried I am that I bought it too big. I'm 6'0 about 210lbs and wear a size 11 boot. I'm a begginner that can go down greens steadily without falling (most of the time). I don't know if this even matters but i'm fairly athletic. I've come to terms with the fact that I should have gotten a smaller board, the only thing I'm hoping for now is that this board is not completely unusuable. Like I said, the day gets nearer and I panic more and more. Can anyone tell me from their experience if this board will get me down the mountain at least for this season, maybe I'll invest on a shorter board for next season. Anyone with similar stats as me? According to the size calculator, I should be riding somehwere between a 160-162. Do 3-4 cm make a HUGE difference? I've heard everything from weight is the only thing that matters, to skill, to height, to style. Thanks!