This is offten due to cultural Imprinting: "Shut Up and Just Do Your Job" or "You Are Not Being Paid To Think". It is hard to get over those early imprints.

Use this forum to start expressing yourself. It will make a good start. Also try expressing your self with art of music and post it online to see what others have to say about it. There you can read rejections or support with the insulation of the computer.

Then work on speeking up to others in real life. Offten our fears are just make belive senerios.