Yeah, using your thrusters on your suit also uses your oxygen... how fast do you want to fly?
Once your thruster switches off you keep drifting in the your last direction, unless you hit something then you bounce off it and it off you and now you have a new vector and most likely cracks appearing in your helmet...
You start with a suit leak and limited oxygen storeage hence the laser like focus on finding the next bottle of O2. Once you complete restarting one of the cores you repair your suit and oxygen system and you can breathe for longer and go for longer trips, One of the cores you have to repair should restore your thrusters back to normal and not use your O2 supply, not done that one yet but at least I am now able to travel between the bits of wreckage without worrying too much about not breathing