Make sure you use a windscreen of some kind with your condenser; either the "mike condom" type of foam cover, or a separate mounted mike screen/pop filter. This not only improves the sound of most recordings (in some cases, you want it off, but not for vocals), it also protects your condenser element from moisture that can seriously impede its performance.
Play with microphone angle, placement, and your voice; you often don't need to be as close as you think. Cardioid pattern mikes (like yours) can have varying amounts of the "proximity effect," which increases bass response the closer you are to the microphone. You don't want to be too far away either, and you have to watch signal level, so you need to find the "sweet spot" for your voice. Ask someone to come in and help engineer for you to make the job easier, and if you will always be recording yourself, in the same spot in the room (if your set-up is permanent), then you can even try marking an "X" where you stand for future reference (once you get the sound you're looking for).
Finally-- Are you aware of the "Focus Control" function of your Blue Spark? If the switch has been in the "Normal" mode ("out" position), I'd try switching it to the "Focus" mode ("in" position) and see if that helps...
GJ