consistently getting placed with and against people way higher than me

so umm, on my first account I placed bronze 3. I tried to go with it and reach at least silver, but i was still losing losing tons of games after placements. I created a new account to get a second try and placing higher.

Anyways, I'm not even level 30 yet, and I am consistently getting placed with and against mostly platinum players. i'm even pitted against more diamonds than golds. I'm losing lane (mid) consistently and feel like i drag my team down. i still get some victories because my teams pick up my slack, but overall these games have been a hindrance rather than a help to my confidence.

If I'm consistently losing lane, am way behind in cs and kill participation, and ending up with negative kda, why do i keep getting placed with such high tier players?