I think online is a lucky dip, yes there will be genuine trustworthy people on these sites but unlike real life you only see what they want you to. The visual clues are missing, such as facial expression & body language.

You have written about social anxiety so this may be a challenge to you, but maybe trying more face to face interaction might be helpful - not necessarily to date but to make more friends. A lot of people meet through friends of friends so it could lead to something more but most of all it would widen your social support system.