DoctorObviously said:
Why can't I be myself with another person?
A lot of advice that centers around how to act on dates, or how to converse with the opposite sex, aren't about masking your identity so much as putting your best foot forward. Projecting a positive impression. If "yourself" is about expressing your values and interests, by all means...be yourself. If "yourself" is being neurotic or depressing or needlessly confrontational, then you're not "being yourself" so much as indulging your desire to act however you please and then griping about the consequences.
Dealing with other human beings...romantically or otherwise...isn't terribly difficult, but it may require stepping outside your comfort zone. You'll often hear that you need to "be confident". Not because you can never show insecurity in front of a woman lest she tear you apart, but because CONSTANT insecurity is wearisome and not particularly attractive (in either gender). You don't need to be in a good mood all the time, but if you're looking to make a strong first impression I recommend not showing up and doing your best Eeyore impersonation. And on, and on, and on. No one has (or should have) a sense of self that precludes them being happy, or confident, or pleasant, or patient, or kind. If you feel that you do, you need to forestall dating until you've done some work on yourself.