There's other cool powers too. Like flying. Turning into a swarm of bats - either normally to fly, or as a form of teleporting. You will be faster and stronger. Your senses will also be greater - for example, literally hear a web being spun, or see the surface of the moon if you look hard enough. There's also turning into mist. You can also control bats too.
Not rude at all. You don't have to feed all the time, so you can wait. But the longer you wait, the more your hunger will grow. Which would be dangerous if around a lot of people. You also have a second sight like x-ray vision where you see blood vessels, nerves, heartbeats, etc. You could use clinic blood bags instead if needed, which might be safer so there's no worry of losing control? Or there's an alternative of ingesting animal blood instead of human.