Yes they should be muchmuch bigger and more broad.

You lighting with floro should be no more than 2 inches from the top leaf with the fan on them.

However, there is no stretching, so you may want to look at your lighting as well as other issues.

They have no bizness getting fed Miracle Grow.
They have no bizness getting any nutes at all at 3 weeks.

Good soil.
7.0 pH water when almost dry.
Floro lights 2" from top with fan.

Do ONLY this, AND NOTHING ELSE for 4 more weeks and you will have a small tree...

Good luck.