workinonit, Do you have this problem during one-on-one convos too? Because lots of people have issues showing their true personalities in front of large groups of people. It’s very normal and there is no reason why you should push yourself to change that.
If, however you are more shy and reserved than usual during one-on-one conversation and small groups, it might be worth working on it so you can enjoy socializing more.
Also, you mention that you are much more relaxed and expressive at home. But are you also comfortable around extended family, neighbors and close friends? Is this “problem” only among acquaintances and strangers? Or are you shy around people who you know well too?