The biggest definition of asexuality is not feeling sexual attraction. Arousal is different than sexual attraction though. (attraction is usually described as feeling like you want to have sex with a specific person, while arousal is a response to a stimulus). There are aces who feel arousal, so that I’m and of itself doesn’t mean you can’t identify as ace.
While the most prominent definition of asexuality is not feeling sexual attraction that’s not the only reason people identify as ace. It’s perfectly okay for you to identify as asexual if you feel that asexuality is a good way to describe your sexual orientation because of your fear of bad things happening during sex.