Ok, As some one who loves mill decks I will start with one huge disclaimer:Mill decks are hardly going to be super competitive. You might win a few games here and there but if is very little chance that you will win a FNM with a mill deck
Beyond that, I would say you need 3 Ashiok main deck. You are running no creatures so you will want something to kinda protect yourself with by stealing the opponents creatures. It is also a free mill 3 per turn so that's nice. You also have only 4 ways to get around Demonic Pacts lose the game ability so I am not sure what this card does for you except to lose the game turn 8 if played turn 4. I also think you need to move up to 26 lands minimum with this kind of control deck.
Do you have a win condition outside of Mill? Mill is usually better as a secondary win condition as you try to play the average control match. Counter spells and wrath effects and get into the grindy game where you have the time to wear them out.
Send to Sleep would be better off as more counterspells or being turned into lands
I am not sure what else there is to say.