How do i make my shoulders more built?

i have an issue where my clavicle bone (end of the collar bone) sticks out giving me basically bony shoulders.im a rower so my left one sticks out more because it. is this just the way im built or is there shoulder exercises that i can do to beef them up and hide the bone?i do train loads but its not doing anything. i want more build shoulders my girlfriend is always pointing out how much she loves well built shoulders and well erm yeh help!!!