Is it normal that i feel dread when i have a chance to date?

I am an 18-year-old woman, out of high school. Lately I had been feeling worried men would take no interest in me because they would always approach my other female friends instead. When someone did, a nice guy though perhaps not my type, I felt my stomach turn to lead and drop and my insides went cold. I am quite good at holding in my own emotions so I played it cool but I felt so panicked! Wasn't this what I wanted? It's a while later and I have been messaging a guy I was starting to have feelings for. This didn't scare me and I was wondering how I would go about asking him out or if he would ask me, but when a mutual friend asked me how I felt about him I was full of fear again! Why does the notion of having a relationship scare me so suddenly?! When asked if I would date him I said yes to this friend because I had thought to myself that I would! But even now, hours later, my heart is pumping and NOT in a good, happy, romantic way. It's a feeling like I'm panicking. Is this at all normal??