blue dream auto indoor, slow growth

Hi everyone

Two weeks ago I planted 2 seeds of blue dream auto.
That are the info you could appreciate to understand the situation:

• Light : 2100 k agro
• Temperature : 68-77 F
• Ground : light mix
• I'm using Hesi tnt complex (lower dosage than suggested because I wouldn't risk overfert )
• I don't have any tool to measure Humidity but I spray leaves with water when they looks too dry.
• Irrigation: probably I exceed , but then I stop giving water for a week to be sure that the soil was dry.
• One plant has strange leaves, they seems to be damaged, but i don't understand why (the two plants grew in the same conditions)
  
• Moreover among the two plants there are 6 cm of difference !!
  

I've never seen leaves as that and i'm very worry because even the new leaves seems to be damaged in the same way.
Anyone could help me ? i wish I could solve its growing problem as soon as possibile
ps: I apologize in advance for my english

Thank you all

I would stop spraying those seedlings for a week or two
and see if that helps..

/might be some kind of light burn but its hard to see in the pic/