Unofficial relationship stress

Hi everyone, ive been lately becoming worse mentally and honestly i think its what mostly is ruining my unofficial relationship with this guy. We argue constantly, its all a complete mess and we arent even together yet. We love each other all of that stuff but we argue constantly and the stress of being unofficial is really taking a toll on me. We cant show that we like each other in public and when were trying to cuddle or hug etc when alone im always on high alert cause im scared someone would come in the room or someone would see us idk. Its honestly exhausting being on high alert constantly while i have enough stress at home. Most of our arguments are also caused by me id say. Obviously i feel like absolute *** that i cause so many problems before were even together bur years of watching how my family acts has shaped me into who i am today, yelling at him cause how else could i be heard? We argue over how he doesnt show he love me or care about me really, or over little things, again i am a problem cause i get mad over little things but idk how to change i really do feel like a horrible person, he tries to change what i dont like or what he could be doing wrong but i just dont do *** about changing myself. One thing i know is that ive been this way cause the stress of not being official has been slowly tearing me apart, as i said the constant alertness is making me too stressed. But mostly this is about how do i change myself too and genuinely try? On top of all my school stress and mental health problems like severe anxiety, deep depression and ptsd? I know they could be affecting my relationship too.