Hey!
Plants need way more moister in the first weeks of life.
If the soil is constently dry they take longer to grow.
Don't over water but you're definetly under watering.
I would take the PH down to 5.8, at this stage nutrients are better absorbed at that PH.
If your using a light or heavy mixed soil, you don't need add nutrients until 3-4 after being planted.
It does look like a bit of Nitrogen deficieny but it could be because of the prior mentioned stuff..
I recommend you water more, to give more moister in the roots and fixing PH, RH seems. fine.
If that doesn't work add a bit of nutrients.
Hope this helped.
Good luck and happy growing!