Let me get clear.
There are pros and cons about destroying a turret earlier.
It is true that destroying an enemy turret earlier at higher elo MAY lead to cs disavantage. BUT, you take control over a large piece of the map. If your jungler is decent, he will keep that area warded and he will also take enemy wards away. If the enemy pushes the lane a little, he will be way further from his tower than you from yours.
That means, in lower elo, it's almost aways better to take turrets earlier. If you took all 3 front turrets before the 20 min mark, the enemy team will most likely surrender, BUT, you must know how to make use of this advantage.
As HnLima stated, having a good team composition is almost crucial. Even if you are very good playing X champion which deals tons of damage but has no CC (Corki, Katarina, Olaf...), if you feel your team has little CC, try asking your team to get a little more CC, but you should be able to play some champ with good CC too.
I cannot stress this enough, keeping your team's mood good is the most important aspect of the game. Even if you lose, it's already a victory if you had fun. Not only you, but all the team.