Why am i getting small harvests

I just harvested 2 plants with a total of 34 grams dry. My friend grows the same strain. (critical kush) and gets 3-4 oz a plant.
I use the same set up. Bionicare nutes. I put co2 gens in there and have a 600 & 400 hps. He only has a 400.

Now, i fim. Would that make the harvest shrink, it got way more bud nodes but would that effect the overall weight
If you have any tips to help me out I would greatly appreciate it

Room temp high and low?

Did you FIM properly? Because you may have damaged the plant by topping it too much. Try your next grow with exactly the same conditions/light, and have two plants - one you top and one you don't. See which you get more off ---> Profit.

Lets see pics of them

Maybe your grows just differ more than you think. Also could be a higher yielding phenotype. Lamps could be newer\higher quality.

What exactly are you growing in?

There are more variables here than I think you realize. But 34 grams out of 1kw total means something seriously went wrong. You could have been overwatering the entire time, you could have been over feeding, maybe your temps were too high, or too low. Maybe you didn't have enough medium.

There is a lot more involved in a grow than the nutrient type, genetics, and amount of light. Hell, you could have a different strain completely and the clones that were bought could have been mis labeled if you did buy the cuts.

What size planters?
How close is the light?
Do you have good airflow- including intake/exhaust?
How do you water & feed?

We grow it as well- and let me tell you- they respond BEST to LST...
if you FIM you are creating extra branches on an already branchy plant.. DON'T!
Just let her go until she has 6-8 sets of branches and start tying them down....
Use a BIG planter...
they should be in a 5-7 gallon MINIMUM as these girls like a longer veg time.

Be sure the lights are cooled and down as close to the plants as possible.

Feed only 1x a week mixed according to a feeding chart, and giving them enough solution to totally saturate the soil and get a little bit of runoff out the bottom of the planters... DO NOT water unless needed between feedings- meaning the top 2 inches are dried and the planter is light....

Did you count the days to harvest correctly? It doesn't start day 1 the day they go into 12/12-- they take a while to start budding-- so the day they actually start to actively bloom is day 1... so you may be cutting them early.

Just saying-- so many things effect the yield-- we just "bottomed out" on a grow because of the planters-- too tall, nit wide enough, and the drainage holes not on the bottom but about 1/2 inch up--- so instead of saturating the soil- it was running down the sides of the planter, most of it going out the holes and some pooling at the bottom... forming a solid brick of soil 6" deep at the bottom of the planter.... the roots couldn't penetrate... so the plants were stunted at week 5 of flower... never got any bigger...

Check it all!!!

I'll bet he vegg'ed for longer than you did...
Longer veg time = bigger yield...