It sounds to me like you are not relaxed on your bike (understandable for a newbie). Focus, when you are riding, on having "chicken arms" as Keith code would say...nice and relaxed. Your torso should not be taking the brunt of your riding, even at long distances.
The other problem is that your reach may be too long. You look like a tiny girl on a big bike. There are ways to get the handle bars back toward you a little more to get you a comfortable riding position. Your boobs may be laying on the tank because you are having to stretch way to far to grab the bars. Definitely look into that. If you are stretched that far, you will never be relaxed while riding.