Is it normal to be unsure whether I'm very happy or very sad?

"if I was nice to everyone and did as I was expected to, everyone would like me"

That is not at all how it works.

I wish it were, but it's not. Being nice does not save you from the wrath of craziness, there are even some that will dislike you just for being a nice person. People are going to hate you no matter how you behave or look and there is nothing that you can ever do to prevent it. Sad, but true.

Keep working on being happy. After a few years of practice it will start to feel more real to you.