So this is my bike..


I've recently been buying a lot of parts for it, but have one major problem with it. I find my self wanting to sit farther back on my saddle constantly. I have my seat set MAX as back as it will go back as you can see form the picture. Do I need a new post?? Or a new stem?? Saddle?

I'm seem to always be pushing my self back onto the back part of it to get comfortable. What do I need!?