Zaz your small growth can be from a number of issues from improper light source to out of wack soil problem with diagnosing issues is were not there or no the strain and your environment,, Curling leafs can be a number of things from and can be a very inherited gene trait
Now what you need to do cause for 3 weeks there is obviously something wrong ,,
Temps lights soil ,, ph etc
My guess is a imbalance in soil causing plant to do nothing or your Light source is 2 week
My suggestions is this go and purchase 1 bag of EWC Earth worm casting and one bag of perlite as well one bag of top soil .
Put half bag of top soil in a pail and then open bag of perlite use a strainer and rinse perite so all dust is removed once that is done put all perlite into top soil and mix then open bag of EWC casting and put half of that into the top soil mix well then i would carefully transplant that seedling into a new pot and new mixture , i would then some how collect rain water and use that to water your seedling Cheers 4th week seedling and 2 feet tall started under t5 and out side in sun now 3 weeks 4 weeks old rain water only and that mixture with EWC and grass clippings as mulch
