I have short stocky legs. My legs are very very strong, but I can hardly lock in a closed guard on most guys I roll with. My feet lock, not my ankles so it is very easy for my partner to break open my guard. What is my next best option? Should I focus on butterfly? I learned some nice sweeps from butterfly this weekend during a seminar. Is it wise for a newbie to work on something like this or should I stick to attempting closed guard for now?