Maybe, instead of worrying about a weak spot and running off to cross train, that is if you are happy with your current training milieu, perhaps you might try talking to your shrfu and see what he has to say. Sometimes, what you aren't getting right now doesn't mean that you are not going to get it. It may simply mean that the emphasis isn't immediately on ground training.
Depending on which style you are studying (I'm not familiar with the style you named), there may be more of an emphasis on stand up fighting, kicking and striking, as opposed to ground fighting. It is, after all, not strictly a grappling art, I would assume, not a Chin Na art, but still Kung fu.
Granted, many people are running to BJJ or what-have-you to fill in perceived weak spots, and they may not be there, other than in your hurry to become the ultimate self defense expert/fighter. Kind of curious to see if anyone can come up with their own answers based on what style they are working, as opposed to running off elsewhere to find what they may, in fact, have in their head already. :boing2: