Your execution won't matter without basic fundamentals.
Getting better is a lot like being on a sports team. You analyze film, form strategy, and apply knowledge in practice until it becomes second nature. I'm not going to sugarcoat it, Litchi (tha gawd) is not for everyone. She is a character that you have to sort of click with to become good with. This isn't to discourage you, but to give you some insight as to where the problem may lie.
As far as defense, what I'd advise is to study other chacacters' blockstrings and gatling routes. It's easy to block something if you know the usual path that leads into it. Try not to get down on yourself. Experience is your greatest teacher in fighting games.
P.S. study as many characters as you can. Less wtf moments that way.