Id offer a compromise especially if you race in a no-spinnaker class ...
For the 'light and flukeys' Id keep what you have and ADD to the sail inventory ... and consider a flatish-cut free-flying 'racing cut' 150% 'drifter' (with moderate 'shoulder' high up towards the head for max power (for accelerating) in the light winds but yet flat and with a precise flat luff 'entry shape' ... enough to affect max. speed) .... either made from 1.5 oz. ripstop nylon or 2-4 oz. dacron. Such a drifter will have its 'luff wire' (super strong high tech polymer line) included in the luff sleeve ... just raise the sail and 'pull the halyard tight to affect the proper luff shape - like you do with an asymmetric spinnaker. Such a sail will need 'special design' from the local sail loft as I suggest a 'moderately large shoulder' aloft but flat luff entry shape for decent pointing ability if needed when even the 135 wont perform in the 'super-lights'. Use the drifter on the reaching legs, and drop/peel the drifter and unfurl the 135% on the upwind beat. A drifter is usually a 'lower cost' sail because of the easy to work and lighter weight materials. Youre not going to get such a sail from a 'mail order' sail loft.
A 135 will usually perform much better when beating in comparison to a 150 especially in the 'light winds' where a 150 usually always suffers from flow 'separation' along the leeside especally in the aft sections... in the light and flukeys there usually isnt enough 'energy' in the wind to keep the leeside flow streams attached when youre sailing 'aerodynamic', youll have a better chance to keep the flow attachment with a 135 (or even 'smaller) ... youll need a FULL set of tell tales and 'gentry tufts' to discern this.
Method: upwind, use the 135 until after rounding the first mark, then raise the drifter on top of the 135 and then furl the 135 when on the reaches. Going back downwind, turn the leeward mark and change/peel back to the 135 ... and youll have the 'best' sail up for each leg, especially on a triangular course.
If you sail olympic windward-leeward then the 135 will probably be 'best' overall (especially if you 'tack downwind' to keep your apparent wind speed 'up').
Im not a big fan of BIG genoas when racing in the 'light and flukeys' ... too unstable and vulnerable to 'separation stalls' going upwind. To me, BIG is only useful when going 'down' or 'across'.