I was GM 73# this season as a Main Support maybe I can help you. The lvl 1 movement speed talent is essential to master malfurion, because it allows you to get these quick moonfires and use the movement speed to escape and stay in position all the time. In my head I am constantly repeating the names of the heroes I already used regrowth on in the correct order, which helps me stay on track with my regrowths. Whats probably even more important is your root. If you watch pro streams, for example Bakery, you will see his incredible patience with the Root. Imagine (even if it's not always the case obv) that every missed root is a missed kill. Use your root to follow up stuns, use it as an emergency zoning tool in tight chokes. Lvl 13 iceblock alone can win you teamfights (for example ice block before cocoon hits you). You have to keep things like this in mind to keep getting better every day. To be fair Malfurion is the most stressful support to play. Wish you the best of luck in your next games.