I weight 154, an di wrestle(BJJ) my friend who is 210.
It's tough, but since they are wider then you, use the flexiblity you have.
[Try] Also, use your legs, if they are using there body weight to lay on you, trying to ware you down, shove your knee's up so you don't waste your arms out. if they throw the legs out of the way, roll with it. Try to be faster (Thinking wise).