No, you are not. When someone is telling you that you are over-reacting, it simply means that there is additional information the other person does not know about. Our past experiences affect our present. When we have trauma or intense fears, or anything of any kind that has affected us in a big way, it can come up in present circumstances. Often we find ourselves "freaking out" about something, and may even blame ourselves for over reacting or someone else, however we aren't seeing the underlying things that cause us to feel the way we do. Relationships is a huge one, for example, if our bf/gf doesn't answer our texts for a while, we may freak out and feel they don't care about us. Because in our past we have felt unloved, or have been hurt to the point we are scared of losing the one we care about. Depending on our level of pain, we react to that scale. The deeper our fears, the larger reaction we have. So it's not about the present situation, it's all about the fears and mistrust that the situation springs up. No one over reacts. If you knew someone was in a car-crash and the next day they flipped out and can't ride in a car, that's not over-reacting, that's acting perfectly in accordance to their trauma. The only difference is, if the person didn't know this person was in a car-crash, they would say they are over-reacting. So don't let people get you down, your fine. You are acting as you should for your circumstances.
It's impossible to know if you're overreacting without knowing what you're experiencing, but you probably have a bunch of anxiety about what's going on. hang in there, friend, and chat with a 7cups listener. : )
Its hard to know if you are overreacting to a particular situation. And of course it will all depend on the situation at hand. Perhaps whatever the issue is, you can speak with someone you trust about it and get another point of view to help you.
I would say, through personal experience that it never hurts to listen to your body and what it needs. It never hurts to mediate on the issue and ask yourself that question, but at the end of the day don't ignore crucial warning signs.