Is there such thing as expressing TOO much?

I don't know what that means either.
I don't think being expressive is a bad thing. But then, Iv met a couple of people who express too much, and I have to say, it was pretty annoying.
I guess it depends on where you express your feelings, and to who.
Like, at work, if you wear your heart on your sleeve, then it will be hard to build good relationships with your co-workers; people: and it will be hard for other people (including your boss) to deal with you; plus it will be difficult to move forward/ahead fast. You work in healthcare, so you probably know what I'm talking about.
As for love. It is always best to keep to yourself. Don't give out too much information, about you, and about how your feeling. How would you feel if you were with someone who told you EVERYTHING about them. I know in words, it doesn't sound so bad. But in reality. itz not only annoying, it takes away the mystery, and excitement, doesn't it? Guys like challenge, so giving them so much of yourself, makes them lose that. drive. If you are just starting to go out with someone, then just answer his questions, briefly, and save details for later on when you know he is crazy about u. Try to stay mysterious with men. it keeps them wondering and thinking about you more. That way, when you do say something about yourself, they will be ALL ears, and very eager to know.
I understand you are naturally expressive. and I'm not saying you should change that. Just watch who and where you express feelings to.
Always remain an open book to your family, and close friends. they are the people who will really appreciate it, and will accept it, no matter what.

I'm exactly the same way. It's actually gotten me into some trouble because people have thought I've been lying or not being truthful. I guess it goes back to 'actions speak louder than words' or 'talk is cheap'. I don't think you should ever stop expressing yourself, but maybe try to find other ways that aren't so verbal sometimes.

Yes and many guys would take advantage of it. I wear my heart on my sleeve all the time and I get so many guys used me and lead me on. I think being mysterious is also the form of defend too. I don't think you will ever change because it is part of who you are. Just need to careful and really think heart before you jump into another relationship. As for me I give up and I think I'm better off being single. No pain and no tear.