Yeah man, 4cm is a fairly large jump. But I was 120lbs a couple seasons ago and still am about 5'8" I ride a 147 and a 150. For most jibbing you want something below the chin, maybe an inch or two. If you're more into kickers and using your board to ride as well, 147 is probably fine. But if jibbing and rails is all you want to do I would look into something smaller. I know Atomic Hatchet comes in a 145 and so does the K2 WWW. Both are pretty soft (K2 is a bit softer). I would recommend maybe a Signal Park Series 146 if you want something a little bigger for all round, but is soft enough for you to lock down a nose press and smooth butters. Signals are super soft and you can typically go up a size on the Park Series for a little more stability because they are so buttery for jibbing and very light.
But for sure, 4cm is a difference you will feel. If you're just learning tricks it's better to start smaller and work your way up. K2 WWW might be what you want, since it comes in 145 and is similar flex to the Horrorscope, and comes in rocker too. Capitas are nice, but don't settle for it if you know it won't cut it. I used to have trouble finding a deck until I grabbed a Ride Kink 147, but I'm also a bit taller.