Trying to get mastery 7 on your main only to get an A+ on every game

Whenever I do REALLY good as Bard or Nunu, I sit there. Look at the S- on my screen, or the A on my Nunu screen, and just cry. I just want them so I can stop worrying. ;-;

Well I got level 7 yasuo all u gotta do is give your team the kill or u cs way hard what i do i kill and farm a lot with yasuo then death wont matter farm for days and u will get level 7

And i'm just sitting here waiting for my first mastery lvl 5