You can also try to slash at them while they're in the air, just before they hit you. From my experience, if you do that, they'll keep trying to lunge at you like that until they die, or decide to defend.
Also, why do you only have five hearts? You fight three bosses before becoming Adult Link, and that means you'd get three heart containers, making a total of 6...
-if you're really good at it, you'd know that on Death Mountian, you can do a backflip off of where there used to be a bomb flower, and if you do it just right, you'll land on top of the entrance to the Dodongo's Cavern, where there is a piece of heart.
-On Death Mountian, again, as a child, where you got the spin attack(or where you should have), you could take the ride Keapora Geabora offers you. Once in Kakoriko, jump off the side of the building closest to the Graveyard. Look carefully and fall on the porch. Go inside, and get the piece of heart.
-Also inside Death Mountian, if you're fast enough, from the entrance of the top of the mountian, there should be a wall you can climb down. Look carefully, and eventually you'll find a piece of heart.
-At Zora's River, as a child, you can take a Cucco up to the entrance to Zora's Domain if you're good enough, and then you could use it to float to the heart piece. And later, as an adult, if you have a certian item, you can get another in the same area.
-At Gerudo Valley, jump down as close as you can to the waterfall at the north. If done right, you'll be inside the waterfall, and you'll see a later you can climb up. Once at the top, there will be a heart piece.
That should give you at least one extra heart contianer.
