No, the number of cotyledon leaves wouldn't make any difference at all to your plant (or ANY plant) ... what makes a difference are the roots and the true leaves. If you're really giving it 1/2 gallon of water every day, you're drowning the poor root system and it can't do what it's supposed to be doing. I've got three grows going now, the youngest/shortest of which is about 45" tall and 6 weeks old... I'm giving THEM 1/2 gallon of water a day!! Overwatering is the quickest way to kill a plant so you need to cut that back to about 1 cup a day (if you need a measurement!)... and don't water every day (I don't know that you ARE but am just saying that as a precaution)... wait until the pot is super lightweight before giving it another dose of water or nutes.
I would also pull up your PH to at least 6.0 as it's a bit low for a soil grow.
She's actually a good height for her age, you've got good nutes going - so there's plenty of potential here... just don't drown her! She'll start drinking more as she gets older/taller.
Good luck!