Is it normal to feel and act oppositely?

I have been diagnosed with severe anxiety and seem to have the same issues. I have a goofy side and then a "whatever, I don't care. Leave me alone" side. My dad has described me as a goth hippie.

I spent over a year in the same limbo your in; I still feel like I'm in it sometimes.
The only advice I can give is to find people you can be yourself around, as in the REAL you, if that means anything. Face the fear of being serious in front of people, it's a huge release not having to try to put on a show for everyone all the time.

There is no way you can do what you are talking about. You do it only in some circumstances not all the time. Example:if you meet a chick and feel attracted to her do act mean towards her?of course you don't. Some emotional responses have got to be genuine no matter how hard you try acting the other way. And by the way there aren't opposite emotions ,it is not like:i am feeling happy and cheery=i am feeling white. Everybody acts from time to time. Who does it more who does it less but it still stays a coping mechanism we use when we are afraid of being ourselves because of fear of consequences or to trick people into thinking we are feeling one way so we can get a genuine emotion as a response and get that feeling of power and security out of emotionally manipulating somebody into revealing themselves while we hide our own emotions away. That is acting in real life and everyone does it to some extent for a variety of purposes. You might be overdoing it tho. Too much of anything is never good. People do not take you seriously because as you badly fake emotions you give off selfcontradicting signals meaning to who is in front of you:i am not serious i am not really feeling this way. Plus the meds you took kind of slow everything down and literally turn off other ones so acting is just one of the many ways you automatically try coping with your anxiety and lack of spontaneous emotions. They even teach how to fake emotions better.it is called "cognitive therapy". It is probably one of the approaches to managing your condition you will have to eventually try anyway.

I've got social anxiety and I've found myself having two different sides to me. It's something you've just got to work on, to bring out the more serious side of you in front of other people. Give it a try one time, and you'll surprise yourself and see that you can be taken seriously :)