Is it okay if I avoid my sister as much as I can?
What makes you want to avoid her?
She is too much for me, I can't stand her.
Nothing says you need to spend tons of time together, especially since she bugs you so much.  But it's not okay to completely avoid a family member.  Try speaking to her about her behavior.
She is a drama queen and I can never say what I want. I'm fed up with her.
Some people have a taste for the theatric and your sister sounds like one of them. Give her some space and let her settle down. There's nothing wrong with being selective with hanging out with her either.