I'm going to be hosting historic combat workshops as soon as I get permission to do so under the auspices of SCA, Inc.. Part of that will be period grappling, which might be useful for you.

Try walking around in stance through your apartment or wherever. Practice slope steps, passing steps, girata, and lunge around until you get more comfortable with everything. Find your most balanced point (keep the knees bent and the butt low-- no, lower than that!) and do everything from there until you can stay there forever and be comfortable.