this is not bad start,this can happen usually in common scenarios.
like if u lose pistol with no kill this is 0-1
if u force next round and get no kill this is 0-2
if u eco next u gonna probably go 0-3
then next buy round there is a chance that u go 0-4.
this is not a bad start dude,sometimes i start game with 0-7 then end up top fragging.
u need to just focus on team win.
but if u really cant move over it,here is my tip.
try to bait at the first 3 rounds,not bait obviously,but dont go first and try to stay behind someone to trade him,get some kills then start playing normally.
but for me,i dont get tilted even if i bottom frag,unless i miss my shots,but ofc if im going first and dying for team im not tilted.
but if i see shit teammates that cant trade,i start little playing passive and trade them,cuz cant die always and watch bots clutching.
also if u have bad day(everybody does),just try to play more passively on CT,and try not to stay last alive on T.
sry for long comments but hope it helps