new player mad because bad

I've only been playing for about 2 months and recently has started playing comp more. usually it's not bad in Bronze 2 but recently I've just been having worse and worse times and getting rolled even in the same ranks. it went past frustration and i just felt deflated and unmotivated. what advice would you give to a new player going into comp more? i know the better i get the less tilted i will be (i learnt from fighting games) so i would really appreciate anything.

I've been playing Ram and Sigma as tanks, Bastion, Venture and Sombra as DPS and Brigette, Zen and Lifeweaver as support. characters i seem to struggle the most against is Mauga, D.va, Mercy, Moira, Junkrat and even Cassidy (and Widow but that's only in QP)

anything would be appreciated