Hector looks fine, these are very slow growing plants. Fertilizer can't increase it's natural growth speed.

Thanks! I was worried about him. So, when will he start to grow more?

I don't know if this Drac is a seasonal grower, taking a rest during the shorter days of winter. Glacially slow at any time, never observed a growth spurt. I've tried giving mine a bit more sun while outside but it just burns if the sun shines directly on it except very early in the morning.

If you have just the one plant, it might be worth getting distilled water for it. Dracs are 'allergic' to tap water chemicals.

Oh ok. Would it be good to use the chlromine treatment drops I use for the fish tank to soften the water?

IDK. Not something I've ever researched or discussed. Does that negate fluoride? I do use some tap water for the short time plants are inside for winter, then use rain water as much as possible while they are outside. I have way too many plants to buy (or transport) distilled.