Why do i act soo strange around people?

I get really wierded out when i talk too a cute guy over the internet or in person... i feel like i need attention too make me satisfied.. and another thing is i choke on my wordss alot when i talk too someone and they think im stupid.. how can i open up more and actually live in reality and except people for who they are... and i also act really wierd around pretty girls and they get the vibe of me being jealouss... how can i get over this? this is keeping me from getting a bf.. oh and i also feel like my moos changes all the time.. ill just start thinking about my mood changing like ill make myself happy then sad then jedalous like my mind races.. what can i do? and i dont wanna go see a doctor or a theropystt.. i just wanna know whats holding me back from living in reality