We're just kinda buffaloed, because you say you planted, then 12 days, then 7 days, but you never really gave an age of the plants.
Don't get all defensive, we're trying to help, but we need an accurate time line upon which to base our opinion of 'is it, or is it not' slow growing.
To be honest, I don't remember seeing anything about months, but we're not trying to be assholes about it.
Your plants look fine, and if there was a problem that was visible, somebody would mention it.
Except for the one top stem on the one plant, they look fine, the one stem is kinda lanky, but just let it be.