I went through a similar experience in high school, having no friends for about a year and a half. To answer the paranoia/low self esteem question I've found what worls best is to move slowly with every encounter. Don't reveal too much personal information with friends or potential loves interests, let it all unravel slowly and in its own time. You'll create solid friendships that way, when trust is slowly built up over time it becomes very strong. If you feel paranoied about one of your friends take a step back and think logically. Write it down or put it out of your head. Feelings of paranoia and insecurity usually stem from overthinking a situation. The term "sleep on it" is a cliché but it's great advice. You'll have a whole new perspective in the morning. I'm kind of rambling but hopefully that'll help some aspects.
