You don't generate points other than those abilities (or perhaps Shiv, but I don't even have that on my bars anywhere). SS sucks with daggers, though. You should always use BS when it's possible, which is basically always except for parts of Aran and solo farming.
Keep in mind that Energy is our limitation, not cooldowns for a number of other classes. Backstab essentially has a 6 second cooldown like Mortal Strike because that's how long it takes to get the energy (not counting Combat Potency or Tea and such). The difference, and one of the beauties of the energy system, is that because energy is our cooldown we have much more freedom to not use abilities immediately upon being cooled down.
So if you've got 60 energy but you're not behind the target, you can wait all the way up until you would lose energy due to a regen tick at 100 and not affect your DPS over a fight that lasts long enough for you to do so. In contrast, a Warrior can only use Mortal Strike 6 seconds after the previous MS, so if he does it at 7 seconds, he's just lost that 1 second as far as MS damage is concerned.
It's one of the fun things about a Muti build is dynamically deciding when to use your finishers to maximize the number of abilities you can use while Find Weakness is up from the previous finisher. If you just do it when you've got the combo points and energy, you'll only get 1 Mutilate off (assuming no Ruthlessness energy) because the second one would take 12 seconds to get to and FW lasts 10. If, however, you wait until nearly full energy, you can get 2 Mutis and another finisher off under the FW. If it's SnD, however, you have to decide if you want to let SnD drop for slightly more regen time or refresh it as it wears off, potentially sacrificing FW benefits on another ability a bit later. Sadly, Muti lags far behind Combat builds in sustained DPS output capability and is not really viable for raids beyond Kara.
I've gotten quite a bit off track here, but the point is that you should almost never use SS as a dagger Rogue in a raiding environment. BS is a far better use of your energy with that kind of a build.