Humidity vs. Air flow - I can't have both

Hi everyone. You guys have been really helpful.
Because it's winter and pretty dry here in Texas, I'm struggling getting the humidity up.
I have 2 plants in veg for about 5 now. One GSC and one SD. They have been growing really slowly, and I'm thinking it's due to the humidity being between 20% and 30% most of the time. I have a humidifier going but I also have an exhaust fan which is sucking out the humid air pretty quickly and replacing it with dry air.
The grow is in a closet and I have the door open with 2 oscillating fans.
When I turn off the exhaust fan the humidity can get above 55%, but I'm concerned about the lack of air flow. I can schedule it so it turns on and off every hour.
I also added a second humidifier and it doesn't seem to have a big effect.

Should I be concerned about the air flow when it's in a closet with the doors open and 2 fans?
Any suggestions, besides don't grow in the winter
Thanks!

I’m growing in similar conditions, below 20% RH and in a closet.

instead of venting I just have a couple small fans going 24/7 and open the closet doors for an hour in the morning and then leave them cracked until lights out.

This way I can get humidity up to 40%, sometimes even up to 55% if I’m vegging a whole canopy.

The only issue I’ve had is slow veg growth.

I would say of the two, airflow is more crucial. Air exchange even moreso.

Really low humidity might cause you to need to water more, and I do believe it will somewhat slow your vegetative growth, but I would say low is better than high; I would hate to have too much humidity but still in such a case, it comes down to airflow and air exchange being the saving grace.

You need a lung room - ideally, you want to exchange the air in the tent with the air in the room in which the tent is located. Then, adjust the air in the lung room to maintain ideal air conditions in the tent.

I keep a humidifier in my tent, and a dehumidifier in my room set to 55%. I have a 6" exhaust fan with carbon filter running 24/7 exhausting the tent air into the room. The humidifier keeps fresh humid air going in the tent, that air gets sucked out and exhausted into the room and the room is kept at 55% (or wherever you want to set it) by the dehumidifier.

I also have a 2nd 4" exhaust fan with duct going directly outside from the tent, bypassing the room. I keep this fan on AC Infinity controller set to 80 degrees F, so whenever the tent gets over 80 degrees F this 2nd fan kicks on and sends the heat out the window. This also sends some humid air out the window but just enough to keep the tent from getting too hot. This also draws fresh air into the room, the room itself is not sealed and has pretty good air flow. I also use a Rinnai propane direct vent heater in the room to maintain temp with lights off, that helps to keep the air in the room dry.

I shut off the humidifier when the lights are off, I don't want to take chances in the dark.

You definitely don't want humidity without adequate airflow.