What does stuttering feel like? Do I have one?

What does stuttering feel like? Do I have one? I've always been quiet and withdrawn. As I've gotten older I don't know if it has been my lack of communication or maybe traces of a stutter. Im very slow to speak and put together responses. I've always tried to put together a few words as a goto response that I know I can't screw up when posed with possible questions I think I might receive. When talking on the fly everyone is quick to notice how slowly I speak. When I don't speak slowly I will often stumble over words. For example, I sat there with a Co worker and kept contemplating bringing up this pick up line I saw on reddit the other day. It was the one about stubbing your toe on furniture if you saw it. I finally decided to give it a shot it came out: "I heard this pick up line, it goes I wish you were a piece of furniture because I would stub, or uh err bang you on everything in my house" I also screwed up somehow on the "everything in my house part" but I can't remember how. But basically I frequently have these issues. I've never been diagnosed with a stutter, but when I was younger I'll had speech therapy for pronouncing S sounds. I'm fine with those now. I just feel like I can't think of the words fast as I need to talk. I'm just trying to determine how to improve myself. Do I have a stutter or am I just socially retarded?