I'm pretty late to reply to this but it's fine if you tell somebody if you like their character! Honestly, the thing about your anxiety is relatable. Social interaction with basically anybody outside of the internet (and sometimes inside the internet) feels awkward. If you compliment somebody's character, you could have made their day just a little bit better. If you feel that unlikeable, try talking to somebody you trust about it. Chances are that they don't find you unlikeable and they enjoy your company!
TL;DR: People like you and you deserve good vibes