Attempting Tartine's basic country bread
You're almost certainly fine. 2-3 days is too early to really tell; and often the most off-putting period, both visually and olfactorily. Unless there is visible mold (green, black, or pink), I'd keep going. 

Your culture is fighting for it's life right now, waging a battle against all the other natural bacteria that you don't want in your starter. Give it a rousing speech after feeding and carry on. Good luck on your new hobby!