I have Bipolar 1, for me I wouldn't really describe it as happy as much as extreme euphoria, with bipolar 1 grandiosity is present a lot of times too, inflated ego.

A big thing to be able to tell if I am manic, is my thoughts, which are very fast, and flights of ideas. My thoughts make sense to me, and my jokes, but other people stand there looking a little confused. Sometimes my thoughts are so fast that I become pretty non functional. Also energy and movement speed for me. I am not just fast in my head, I am fast in everything I do, making me clumsy. The staying up for nights on end. And I also get psychosis. This is how I can tell I am manic, grouping the symptoms. It can be really hard for a manic person to realize that they are indeed manic sometimes.

A lot of the time I will not realize I am manic until things get really severe and I am no longer functioning anymore.

I hope that helped some, I have been diagnosed for for many years, and even still It hard to tell when I am manic till after the fact.