Polo has good advice.
I am still in that situation - but only to an extent. I just literally had to force myself to "pretend" to be happy, social and talkative around people at my work because my job requires me to be. But, outside of work, I just retreat back into my shell.
Once I go out and start socialising again now that I've had top surgery, maybe things will be different. But I think that it becomes a habit mentally for us to withdraw and avoid social situations, so it may be some time before all will be "normal".
That being said, I actually don't LIKE socialising, so I don't force myself to anymore than I have to. I have accepted the fact that my asocial behaviour is half fear and half desire, so meh...
But...again, sometimes just forcing yourself to be the person you want to be is what you have to do. What I used to do was imagine myself as my favourite male movie or book character and sort of project myself in a similar way - not quite "make believe", but more like finding your own confidence through emulating them.