how to seem more open and approachable?

i have every instinct in my body telling me this is narcissistic but whatever. im a 17 year old girl and people tell me im pretty/ attractive very often, but i haven’t made a friend from highschool in my 4 years, and im very lonely. people often tell
me that i’m intimidating and not that approachable, and i don’t know if this is paranoia speaking but i think everytime i speak to people, they look surprised that i actually did. (i also dress different, but people compliment me so i think it’s in a good way). i also can’t talk in a group at all, and i sort of ‘shut down’, like every bone in my body won’t let me speak. i don’t know what to do, i know there’s a lot of people who are better alone but im not. i really like people and talking to them, but no one ever talks to me. it’s worse because people do approach me, but i fumble the ball everytime because im so insecure i can’t imagine trying to engage with them, like im wasting their time. i just don’t know how to seem less aggressive and weird? this is sort of just coming out as a vent post, but any advice?
(also i’m scared of talking to boys because they always seem freaked out and i’m scared they think i’m ugly and make fun of me. like how could i ever think they would
be into ME, you know. so that doesn’t help when i find it really hard to talk to half of the population)