Looks like what you are experiencing is a lack of nitrogen. Be sure your plants are not being over-watered, that your water is at the correct pH or atleast distilled, and try adding coffee grounds into your soil. Used coffee grounds are very high in nitrogen and will give a slow release of nitrogen into your soil throughout the entire veg process. Good luck, I hope your are able to grow some wonderful medicine! :)
A second guess is that your plants never developed a strong root system and can't get enough nutrients to grow. Of you happen to pop seeds again make sure the plants develop a very strong root system before transplanting to a larger pot :)
Aha ok thank you so much, I will try adding coffee grindings.