your tree will do best with a 5-1-3 ratio feed but yours is good. Your tree is to small to hold fruit. If my tree of that size flowers I will break the fruit off so the tree puts energy into twig growth. My best guess is your need a bigger pot and more feed. The light over head looks good. My setup for growth below. get 16 hours of light.

I pull air through the root base 2-7 times a week. 7 times weekly after watering down to 2 times weekly when the soil is dry just before the next watering.

Tree is 37 inches tall and about 8 months old since the first leaves came out from the grafted bud. It has flowered and all the fruit has dropped because the tree can not supply the needed energy for the fruit. If the fruit had held on I would have removed it. I feed the tree full strength Miracle Gro 24-4-16 and add a little 28-0-4 to up the nitrogen get close to 32-8-12. I flush the soil every other feeding to get rid of excess of any thing that builds up like salt. The soil runs about 70F and the foliage about 80F.

6b Steve

Try propping an axe next to it! LOL