as a rule of thumb, cisgender people don’t spend a lot of time worrying about whether they might be trans, or if they’re faking it. and straight people, likewise, don’t spend a lot of time thinking they might not be straight! contrary to what gatekeepers would have you believe, people in the societally-accepted in group don’t try to think of reasons they might actually belong outside the group that’s accepted as normal and most routinely treated as human.
likewise, heterosexual, heteroromantic, and cisgender aren’t the default; just as asexual, aromantic, and agender aren’t null identities unless the person in question wants them to be! being asexual and/or aromantic and/or agender doesn’t mean someone is secretly heterosexual/heteroromantic/cisgender.
finally, just as being asexual, aromantic, or agender is valid, being heterosexual, heteroromantic, or cisgender is also valid. if you explore yourself and find that you’re not what you initially thought, that’s okay! if you turn out to be bisexual, aromantic, and cisgender, or aroace and genderfluid, or asexual, grey-aro, and genderqueer… there are lots of possibilities, and none of them make you a “special snowflake”! whatever you decide fits you best is ultimately just part of the many elements that make you who you are!