I like the way you play it and you should be doing this. You want to flank the enemy teams damages dealers and try to assassinate them. It sounds like you may be going in a bit too early. You want your team to go and create some chaos first, or be ready to heal/followup on your initiation right away. If you go in too early or ahead of your team you will just get focused and die. Try to go in with your tank. If you don't have a tank then its probably better to counter initiate or focus...