Lots of people swear by MSM as a supplement, so by all means carry on using it if you like.
But for leaky-gut, I would focus primarily on L-glutamine as this is the fuel that your body uses to build your gut. I would also increase the dosage gradually to try and avoid constipation. But everything that I've read says that for a theraputic dose you should be taking 5-40g a day (perhaps in divided doses).
So what ever level you are on now, try and get it up to 5g as soon as possible, then increase from there as desired.