Its not really a matter of your height and board length...its more about weight to board length. However the most important is a rider's skill trumps the board design and specifications. As you progress and at an advanced/expert level you will be able to ride any board...but the issue will be what is the best board design and size for the type of riding and the snow/terrain that are there to ride....that is why folks get several boards (a quiver)...some days I will bring 3 boards to the hill and then select the best designed board for the available snow conditions...and they range from 155 to a 164.
Roxy Ollie pop in a 141 sounds about right...it will be much easier to progress than the 149
If you keep riding the larger 149 and are determined; there are some potential rewards and pitfalls...steep punishing learning curve...but if you master it...you will have no fear of blasting and it will force you to develop very fine/finesse edging skills. My daughter went this route and at the end of 3 winters, (your size) she was throwing around a 148 stiff freeride board and was wickedly fast.
Last edited by wrathfuldeity; 10-01-2013 at 11:45 PM.