I'll second the Never Summer recommendation. I'm similar is stats to you (5'6", 115lbs, 7.5 foot) and started last season on a low end rocker board. By midseason I was frustrated as hell because all my friends were passing me and I thought I just sucked at boarding. Tried a couple of friends' boards out and realized that some of my problems were definitely being caused (or at least exacerbated) by my board.
After some research I wound up opting for the Never Summer Pandora 145 and I've never looked back. I caught up to my friends in about 3 trips out with the new board and it was just amazing how much more confident I was and how much more fun I was having. I've found it's a lot better on ice than my previous board, rides super smooth on chop, and is still long enough for me that I don't run into major issues in powder. I was also pretty impressed at the durability. I took it out at least 10 times after getting it in the middle of the season and it still looked new.
I went for the Pandora over the Infinity because I wanted the extra flex since I have an extremely slender build and not a lot of muscle. I'm also just not a particularly aggressive rider. If you have a more athletic build, the something a bit stiffer like the Infinity might be a better choice.
I also agree with the others that a 141 would be too short. You might like it at first but I think you would ultimately find it limiting. Especially on trips out west.