I will add that if you want to slow the growth on your tallest branches, instead of topping them you can try a bit of high stress training called super cropping. You can find a lot of info on it, but basically in your case, if a branch is growing too fast/tall, you can slow it down by breaking it somewhere in the top quarter.
You don't want to snap it completely off, start with a section, say the 2nd or 3rd node from the top, and with your thumb and index finger, squeeze and roll it back and forth, softening it up a bit. Then try and bend it at this point, don't bend it all at once, just a back and forth motion until it bends over double, the stem should crack but not snap off, and when finished you want it to hang down past 90 degrees to the vertical.
If you do it right, it should stay bent and hanging down, if not enough you'll find that within 24 hrs it'll be back up and looking pretty much like nothing happened. When done right, the injured spot will take time to heal, usually forming a knot at the damaged spot, but in the meantime this stops vertical growth, and as super croppers claim, they say it can also increase potency due to the plant kicking into survival mode and upping its production of cannabinoids (I'm still not 100% sold on that idea, but the technique comes in handy for other purposes, like stimulating lateral branching below the break point).
It's a fairly easy tech to learn and the worst that can happen is that the broken part dies which still gets the results you want of slowing vertical growth. Btw, I've snapped many a branch while doing this, and so I keep a roll of electrical tape handy - just hold the branch upright and wrap enough tape around the spot (plus about 1.5 inches above an below the break) to support it upright again (you can also use some string to hold it upright if need be). Then after a week or so you can remove the tape and it'll be all healed up. Fun stuff to play with if you feel up to it ;?D