What if I'm this way because of trauma
If you've experienced trauma that it's understandable that you might find yourself in a confusing and scary place. That's ok – it's the natural response to your situation. Having to worry about your orientation or whether you're broken is just another burden and if using the label of asexuality brings you some relief then that's a good thing.
While asexuality is usually not a result of traumatic experience, it can be in some cases. Asexuality describes a lack of attraction, but it doesn't specify why – to be asexual there is no requirement that you be so for a particular reason, nor is there a requirement that there be no identifiable reason.
Ultimately, the label of 'asexuality' is a tool. It's something people use (or don't use) to help them understand themselves, understand others, and connect better with those around them. Calling yourself asexual also makes the statement (perhaps only to yourself) that you are fine the way you are and no one should try to fix you. If that tool is useful for you, there is no harm in using it, provided you are open to the possibility of change.