Just so you know, you can be in a relationship and still be very lonely. Dont let a relationship define who you are. You say you are shy, its not exactly a negative thing. You will meet someone like you, if you are happy within the person you are, you do not need to change. Everyone is different, everyone has different ways of communicating. If on the other hand, you feel like you want to change and improve ( but only for yourself) but start small, take it one step at a time.
As an example, if you feel you are shy, write down what makes you shy and in which particular circumstances, and then try to address that one by one. Nothing will be done overnight it will take time.
Importantly it seems you may need to control your emotions, getting angry at what someone else does, in which you have zero control will just lead to trouble for you, and it not a trait you want to develop as you get older.
Whilst having some jealousy is understandable within a relationship, but having no relationship with someone and getting jealous is your own insecurities.
One last bit of advice: never worry about looking silly, who cares what someone else thinks, you do you. If you have to fake confidence then go for it until you are comfortable been a confident person.