Underwatering or rootbound?

Hello all!
So I've been growing a northern light auto from royal queens seeds and so far it's been a breeze but as I'm nearing the 5th week and entering flowering I'm also starting to run into my first problems.

First a small phosphorus deficiency that I fixed real quick and then a strange one that I can't seem to figure out...

The leaves are drooping but stay really healthy looking and resilient.

It seem to help when I water because it perks up in a few hours. But I heard underwatered plants should be limp, not healthy and rigid.

something like droopy stems and weak leaves? Which absolutely isn't the case here. They stand straight up but the leaves droop down without being weak or floppy.

Am I accidentaly overwatering? I have to do it evert 3rd day for now.

I'm asking because I think I read somewhere that it might be just rootbound? And that it would cause me to overwater?

Im really cofused because before each watering I check the pot and it's rather light.

Oops the picture didn't work for some reason.
But there you go!

Are the leaves heavy and droopy? (Over-Watered)

OR light and limp? (Under-Watered)

It is possible you may not be watering enough when you water. How much water do you give?

I wish I had X-Ray Vision , But I can't really tell you if they are root bound. Just pull it out when it's dry, and if the roots are wrapping around the pot over and over and it's a tight root-ball, you may want to consider up-potting (IF you are still in veg).

I got one of the cheap meters that has light, ph and moisture on it.. It tells me when to water and how close to put my lights.. Ph is not accurate at all. Think I paid $10 for it.. Takes away the guesswork..If you can't push the probes in easily you're probably root bound..

So nice lil update on the situation.
I am indeed in flower and I ended up doing something incredibly stupid that I'm real fucking glad didn't backfired in my face at all.
I did the up potting and the plant was only starting to get rootbound. It had still some space left on the bottom of the pot but all around it started wrapping around.
I was as gentle as possible and overnight, the leaves perked right up and it grows as fast as before.
Glad I got this sorted out!
Thanks for the help!

whatever pot you put it in, put an inch or two of gravel in your saucer. the plant in your pic is sitting in the run off water, reabsorbing it. that leads to salt buildup in the bottom of your pots, and burnt roots, as well as a good breeding ground for root rot

thanks for the advice!
I'll make sure to add some