I'm also guessing you have more experience in the lord form, so how do i feed?
Blood drain (right hand's power) is used to "feed" to increase the perk tree, you have to kill random wild life in the woods and enemies with it, they have to be LIVING doesn't work on dead things since dead blood is poisonous to vampires, though you can switch to melee (click in left stick) and when they are low HP use a power attack Hold L or R trigger and your VL will charge a attack its a random chance if it works but its cool when it happens, your character like wraps his bone wings around the enemy holding them still when he bites them..that also gives Vampire Lord perk tree XP.
In normal form when you don't feed for a day you get Vampire's seduction, cast it on villagers/enemy humanoid living NPCs and you can feed on them even if they are awake by attempting to talk to them..an option should appear (Illusion magic perks cause it to work on higher level enemies my volkihar vampire character is level 81 and it works on all enemies except Maven black-briar and dragons, without the perks from what I hear it stops working on enemies higher than level 15..)