Stepper driver 3.3V 3A
Voltage may be just fine, don't worry about it. But you don't need H-Bridge, you need a stepper driver, similar to DRV8811 or something else, that will limit/control the current and perform steps. To make it by yourself you need a whole project...

While waiting for reply, i want to add something. The voltage doesn't matter much in theory. What depends on voltage (very roughly) is how fast you can go, because the BEMF. But it also depends on you steps profile, etc. In the end, if you will be able to move on exact speed of 3.3V, the mean voltage on phases will be 3.3V. Also i wouldn't be afraid of arcing- it's 12V, what damage could it cause?

If you use DRV8811, voltage will also affect current control circuit. But if you are aware of it during design- it's not a problem.

I am absolutely bored while code is compiling, so i want to add one more comment about BEMF. Usually motor is rated for certain working point. They will say: 1000RPM, 17V, 2A, 20W, etc. RPM is important, but if they take a nice number there, any other number will usually not be round and nice. But 3.3V is nice! That means, probably, it's just a general guidline, meaning nothing special. You will not want to use it with 300V, but 5V, 12V, 24V will all be OK, as long as you don't exceed current and power rating. Both may cause damage.