Fear of Open Water and Huge Crowds

Ok, i was at a lake house with the family and there was a floating dock thing out about 25-30 feet off shore, and the water there was about 6 feet deep. This was the first time i've been on a lake like this since i was about 5 or 6, and i'm fourteen now. But i started to swim out onto the dock and starting having a panic attack. It became hard for me to breathe and my sister had to help me to stay a float. She brought me to the floating dock where i waiting untill my dad brought me back to shore with his bass boat. Even in my pool i've always had a sensation every now and then of terror and panic, as if something were to attack me and i couldn't get out. same fear that came upon me when i was in a huge crowd of people at my sister's college orientation. I looked it up online and i beleve my fear is agoraphobia. i want to know if there is anyone else who has this fear, and if so, how do you cope with it, or if i'm wrong with my self diagnosis?