Am i underwatering her?

*My plants about 4 and half weeks old. (Northern lights auto)
*Growing indoors with temps between: Low temp 66/High temp 82. degrees
*Growing in FFOF (no nutes for the first 3 weeks. Starting at week 4 I've been giving her a generic nitrogen fert at between 1/8 to 1/4 strength)
*Watering schedule is usually once every 1.5 to 2 days she gets 5-6 ounces of water. However when I watered her this afternoon it'd been about 2.5 days from the last time she'd been watered.

Yesterday I went to bed at midnight she looked great, very robust. When I checked her about 13 hours later this afternoon to water her she was very limp. Please see the pictures attached. Is it possible that I'm giving the plant too little water, not enough often. This is my first grow, and I've read so much about people overwatering their plants and killing them, maybe I thought too much into it and have been under watering
mine.

Experienced growers what are your opinions? If not under watering what am I doing wrong here?

yeah she looks thirsty

What do you think is more the issue, the amount of water i''m giving her, or the frequency?

id say frequency as there is a lot of perlite in the soil. maybe water every 2 days instead of 2.5. something you could do is get a watering bulb, it looks like a tear drop that you put into the soil keeps it from drying out to much. just google watering bulb and you'll get thousands of hits

Generally speaking do you think I should be giving more volume of water as well? Soil is FFOF with a additional 1/4th perilite

Watering schedule is good .. I think. Now, does excess water flow underneath the pot when you water ?

No, The bottom of the pot has 4 drain holes of which I've never seen water run out of.

Try getting a feel for the pots dry weight and water when dry...unfortunately there is no magic remedy so you just gotta keep an eye and keep track.

i think if ur never seeing water drain ur not giving it enough water. on my first grow as well.