Sometimes when I breath ill get a very sharp pain in my chest right under my left breast, it feels like light stabbing or something, I'm not quite sure what I can compare it to, when I get it it lasts for a couple hours and hurts when I laugh and cough too... and if I take deep breaths to try to get rid of it it just hurts more. Any ideas of what this could be?

Sounds like a gas bubble. At your age, unless you have underlying medical conditions, and this is the ONLY symptom, there should be little to worry about. You should, however, bring it up at your next doctor's appointment.

how long do those last for because I've been getting it on and off for a couple years now
also I have an extra bone or like lager bone or something I don't remember right in the middle of my chest like where my solar plexus is but a couple years ago I got an x-ray to make sure it wasn't affecting my breathing and it was fine then but could that be it now?

This just happens. Especially during growth spurts.

It also could be your gallbladder. Do these pains radiate to your back? Do you notice them after eating certain foods?

I get them sometimes after I eat the same foods that give me heart burn but they can also happen randomly on their own...
and not the pain is just in one little spot never moves never feel it anywhere else

Most likely it's gas or heartburn.