Try practising with the elbow of the bow arm resting either against the wall or on a table. Then you'll have to get some wrist flexibility to play as the bow movement will have to come from the wrist. And I didn't learn how to play triplets until I learnt "Within a Mile of Dublin" (730 in the O'Neill 1001). It just takes time and patience. The Trumpet Hornpipe is another good tune for triplets. Don't let it beat you - if I can, then you can!