I think some expectation management is due here. 8kg gained and 4% bodyfat lost is pretty solid. You do realize 8kg is almost 18lbs right? And you're upset that other people have gained 20+, right? It's easy to gain 20+ lbs in one cycle, but much of that would probably be water and fat. Also if you're cutting for a whole month during one cycle it's harder to make gains that way, but in my opinion it's better to make clean gains and not end up with a bunch of extra bodyfat, so that probably wasn't a bad move if you were carrying a lot.
That said, if you want to see more impressive gains (assuming your diet is on point) you could try adding deca or NPP to your cycle. I'd run a 12 week cycle, as follows:
W 1-4 dbol 40mg per day
W 1-12 500-600mg Test-E per week
W 1-12 200-400mg Deca or NPP per week
With a dbol/deca/test combo you may need to up your AI dosage, and also have caber on hand for potential prolactin sides from the nandrolone.
If you're worried about gaining bodyfat, then maybe look into tren instead of deca or NPP. It's often labeled a cutting steroid but that's mainly because for some it can lower bodyfat before your eyes while still building muscle. Same prolactin advice applies.
After an 8kg gain what you can expect from subsequent cycles is likely to be less impressive, although at 70kg bodyweight I would have stayed natural a lot longer before cycling anyway, because you still have a lot of potential for growth. Aside from a short stint with dbol back in high school, I didn't start messing with any anabolics until I reached 100kg. And I'm only 5'9"/175cm tall. Granted my bodyfat is a couple points higher than I'd like it to be currently, but I learned how to gain weight naturally.
AAS will only enhance what you're already doing right, not fix what you're doing wrong.