I lost my friends cause i dont use facebook?

[...yo]

Im 15, a guy, and i've had a rough life. I grew up with strict parents who were mean. My brother is a dick too (hes older). I had a skin condition when i was younger and people always noticed it and i felt insecure. By the 5th grade it started clearing up and i had a bunch of friends. I graduated and transferred to a middle school kinda far from my elementary school (thanks to my parents -_-) and had to "restart" my life. I made friends gradually in middle school and eventually knew everybody. I was nice to people because no one ever was when i was young. Im in high school now, and i know lots of people but not closely, like i don't actually know them personally i just talk to them. I want to use facebook, instagram, all that, but:
1. I'm shy because of my previous insecurities when i was younger.
2. Im worried my middle and elementary school friends won't remember me and not accept my friend requests on facebook.
3. I don't want to end up with 100 something facebook friends while everyone i know has like 800 to 2,000 friends because they are all so outgoing.
4. I hate taking pictures of myself.

Also, my brother thinks i have no friends and it hurts, emotionally. I have many close friends but i don't see them anymore. I have maybe 50-60 close friends, but we aren't in touch much anymore. I met up with a few a couple weeks ago and they missed me.. I don't know why i can't get myself to just go on facebook and take an hour to add people. I just want something to do in life besides school and video games and other stupid things +sports which i love playing. I'm not someone who takes it seriously, the only other thing i've used is Aim, and that died out in 2009. I just want to catch up and reconnect/ build stronger relationships with my friends, what do i do? I don't think i can just do it right away, i may need some time but mostly your advice guys!