Mate, i started the exam same boat as you around.... 6-8 weeks ago, i had no ph tester, no temperature gage, no humidity gage and all of that. I ended up with 1 plant out of 6 left.
You REALLY need the equipment.
It looks like you've used too big pots to start them off in. You shud always start small then gradually move them up.
Also, make sure you keep an eye on the temperatures at night, its okay for the to reach 60-65f minimum but i try not to do it and keep mine around 65-70 if not higher at night.
My growth was the exact same as yours at this stage mainly down to that i didn't have any roots in my NFT. When the roots made they're way in the growth trippled and grew from nothing to something so quickly.
What light cycle have yu got them on at the mo?
How often do you water?
What sort of seeds are they?
I've just noticed in the top picture, top left hand plant, further away from camera seems to be growing the best, this backs up the case of using small pots to start off with then transplanting.
I wouldn't be too worried, yu might just have to have an extra 1-2 weeks in vegging and trust me, its worth it!
If yu have any more questions, drop us a line

i'll try my best to help.
Just remember the most important factors!
- Air circulation
- Soil
- Water
- Temperature
- PH
- Humidity (Not too important in my eyes, but it'll be benefical if yu can control it)
p.s.
another thing that has just sprang to mind, those plants aren't in a box or anything they just seem to be on the floor. Is that room 100% blacked out? Cus if you have any light in there its gonna effect your plants dramatically.
Another tip ; make sure you have an osculating fan, if you have a fan constantly blowing wind onto them its not benefical and usually ends up in snapping or miss-shaped plants. So either use a normal fan but point it at an angle where the air will be deflected in different directions or get an osculating one
