Best way to sleep with broad shoulders?

Okay im a girl and i have fairly shoulders. I sleep on my side because i heard its the best way to sleep. Im not sure about that though because my shoulders are killing me in the morning. I prefer sleeping on my stomach but i heard it makes breathing more complicating. I do sleep on about 5 pillows:/ but they are small pillows and two normal pillows. I have no clue whether the pillows are causing me pain in the morning or my broad shoulders.