idk why you are loosing so much, but I have a very serious question.
How did you get put in silver 4 after only winning 1 promo, and then I win I think it was 6 and get put in Bronze 1 that makes no sense to me at all. And also, I understand your feeling. Last season was the same thing with me. Even if you do everything correct, and you are fed, and everything, if your team is sucky, then there isn't much you can do.
What I'm trying to say is if you are doing well and your team isn't, (I'm not sure if you were getting mad at them or not) but if you were, don't get mad. Just congratulate them on every single thing that they do right, and try to nicely give them pointers. This actually happened to me in my last ranked game. Olaf was top and I was j4 jg, and he was feeding irelia like crazy. She had 3 kills at 5 min. I told him, don't go in on her when she is so ahead, wait for me to gank, and I just kept telling him gj even when he would only throw an axe and then run away.
We were so far behind, and yet we still won, so I guess the best thing is just too do the best you can, and sometimes you will get a losing streak, but don't let that get you down, just keep trying.