bigger humidifier.
it costs a bit more buying replaceable wicks, but get the kind with a wick... The ones that put off that visible vapor are the ones that coat everything with a white dust.. .kinda gross for an area growing plants you intend to smoke later. These types are cheaper up front to buy, but constantly have to replace wicks.
for references, i have a 5 gallon humidifier. I need it for first 4-5 weeks of vege and 2 weeks of drying (12-14 weeks total for 2 cycles). I go through 2 wicks per year. Buy the bacteriostatic additive stuff or else you will buy a new wick every 3-4 weeks because it'll be a microbial mess in the reservoir.
The re-useable wicks are okay, but will not be as effective as the disposable paper wicks. I have to use the better wicks for the vege phase, but my drying room is much smaller and a reusable wick works fine for that. So, if it struggles to maintain RH% at all, avoid the reusable wick options as that will only make it less effective.
until you fix VPD, reduce light... that's stunting it. temp, rh, ambient co2 and your light all have to jive... can't force feed it light.