How to get out of Silver Stuck and Tilt

Hey guys so it seems Im stuck in Silver. Sometimes ill duo with my bronze/silver friends maybe not the best idea but Ill have games like 15-6-15 and we will just lose the game because people don't push objectives as hard or the other team pushes harder than us. What are some tips on how to carry even harder? I know to roam and the basics and I usually play mid and cs decently for my elo but ive dropped from S3 to S5 7 LP now and I don't know it seems Ill have an amazing game but my team will stole lose a close game and then i will end up tilting because I get terrible teams. and I notice that the enemy teams im playing arent even good so I get fed but I cant carry the team whether it is they get more barons/dragons and my jungler does nothing... What can I do do avoid tilt and win more games? Shud I duo or solo? Edit: Last game I had a Leona waste ult at baron when it was full hp..