Hey there gnome. Yes your plants are a little small for their age, bit they look healthy. When growing in soil you usually don't need to use any nutrients until around the 3rd week. I also suspect that you have been overwatering a little. You want to let them dry out a lot before you water. These plants like to have a steady wet/dry cycle. If they are kept too moist then oxygen flow around the roots will be poor and they won't grow very fast. But hey knowledge is power and we all still learn in this hobby every day. Don't stress yourself out about the beginner mistakes. Just take what you learn and as long as your next grow is always a little better than the last then that is progress! That is what it is all about. I will follow you on these. If you have any future concerns feel free to ask. Good luck!