My fear of rejection and of not fitting in

After a drive with my friend today, I ended up pondering a couple of ideas about fitting in, and probably one of the things I am absolutely 100% terrified of, possibly above everything, is the fear of being rejected.

Im lying to you, but that's ok, because your probably lying to me, and it's not that I don't want to get to know you, it's that I'm scared of what will happen when I do.

Me and my friend were talking about the idea that we spend our whole lives fitting in and doing what is expected of us rather then what we wanted to do and what would truly make us happy. I honestly think that I have spent over half my life doing what people expected of me. I studied and stayed quiet at school because thats what I perceived my peers expected of me. I studied and passed my GSCES and A levels because I thought that's what society expected of me, and I feel like I was forced in that direction by a sense of social discourse, but I never put my heart and soul into it. That’s probably the reason why I got a 2:2 at university, because I took a course that  never really appealed, If I'm being 100% honest with everyone including myself. I even applied for a masters and started volunteering in something I didn't want to do, because again I felt like I should rather than that I really wanted to.

Also, my crippling fear of rejection stops me from trying things that I should be doing because my mindset is always that there is possibly someone better suited to it than me, never considering what I might be the better person they are looking for if only I just applied myself. This also refers to my private life. I’m scared of meeting new people, because as soon as I open my mouth I'm afraid they won't like me and are instantly going to reject me. I've even dated people and split up with them because I've always had that fear in my mind that they are going to dump me first so I may as well end it before I get too invested and it hurts worse. So I am trying to change my mindset and focus on myself. It’s going to be really hard as it almost goes against every instinct I've come to know as natural, but while I'm still young it's time for me to start following my dream (when I find it) and making a better life for myself while there is still time.