Tilted or just bad?

Last season I played ranked and got to plat. I was really proud of it but then I stop play league for a bit. Starting to play some mmo and fps. When I come back to league pre-season started, I play with some friends on league and it feel like they got better than me. They are like silver and gold. I got carry. Some of them told me that I should start playing league on my smurf because when we get match with plat/diamond players we always lose. They even wonder if I get boosted to plat. I'm pretty upset. I'm not sure if I am tilting or I am just bad. Is there anything I can do to get better?