Are you self conscious about certain traits you possess? That nervous twitch you feel coming on when you're in a meeting or the way you bite the inside of your mouth when you concentrate. Do you feel like you have to restrain yourself when you'd like to jump up and down or yell obscenities? Would you like to let out a long primal scream or just close your eyes and be still? Do you feel like raging about the state of affairs in the world or maybe you just feel like finding that gentle, soothing place and let healing take place?
These are all very real feelings and emotions that we often have to repress or put on standby because of the situations and real world circumstances we find ourselves in that won't allow it.
Let me suggest that when you are playing guitar and creating music you are allowed to go to any of those places. You're encouraged to go to all those places and let it all out! Even if you're on the edge of a stage with 10,000 people watching, you're allowed to breakdown, get weird and come apart at the seams as long as it comes through the sound system loud and clear and without regret. Now let me warn you that this can be very dangerous. There is the temptation to never quit playing guitar or making music, and this can lead to quite antisocial behaviour but...that isn't my concern here. Obviously I'm too far gone.
What I want to get at is that when you are playing guitar, every physical, mental and spirtual idiosyncrasy you have is highly valued and is indispensible. That nervous twitch is a tremolo technique that some won't master in a lifetime. That stutter could be an incredible riff to a generation defining song. That deep spritual longing that tugs at you may find it's way through a somber melody right under your fingers. Let the anger of that damaged relationship out on your fretboard and pull at those strings until you feel a breakthrough emotionally and then release it with a cascade of notes desending the fretboard until you run out of frets and then collapse.
Perhaps you feel the need for restraint in your life. A tight three chord progression and a minimalist arrangement might be the hit prescription for you. These are just suggestions as ways for you to include more of your personality and traits into your playing and writing. What is often seen as a liability in everyday situations can be exactly what you want in your music.
Even if you never intend to play in front of an audience, you will never enjoy the full benefit and joy of playing guitar until you can play without restraint for yourself. Once you close that bedroom door it's just you and your instrument. It is an extension of you. Don't suppress anything. Try playing a simple one or two chord progression while you meditate or think about your day. Perhaps E minor to G with a nice mid tempo strum and then mix in some picking of the individual strings. Find some notes to bend and just explore while you let your mind go where it will. If you think about something tense let it come through the fingers with a wiggle or a hard hit with the pick hand. If you think of something painful, bend. Or perhaps you feel a gentle, feathery strum is more in order. It doesn't matter as long as it is you and you are learning about yourself and your relationship to the guitar.