Still stuck with only silvers

Can someone please please please explain the matchmaking so I can get this shit out of my head. It is so god damn frustrating being a plat player and yet in my fucking promos I am stuck with 4 silvers(some low some high) while the other team has golds/plats...even when I go positive I just lose. I try making up for any lack of warding, i try to ping, i try to communicate. I am now 1-5 on my promos literally every game being with silvers. Anyone have an explanation for this? Also am I going to be thrown into silver because of it?