You can confirm how many shards you have picked up from the Skyshards part of your in game journal. Just divide that number by three (rounded down to the whole number).
Everyone knows the phenomenon of trying to hold your breath underwater - how at first it's alright and you can handle it, and then as it gets closer and closer to the time when you must breathe, how urgent the need becomes, the lust and the hunger to breathe. And then the panic sets in when you begin to think that you won't be able to breathe - and finally, when you take in air and the anxiety subsides...that's what it's like to be a vampire and need blood.
Francis Ford Coppola - BS Dracula: The Film and the Legend