Couple of things:
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You've been playing a lot of Karma support. Aggressive mage supports (basically any support that picks Thunderlords) have become popular in LCS, but they can be difficult to play. Karma is mechanically complex, and you've got to land a lot of skillshots to do well with her.
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You die a lot. You need to figure out which of your plays are getting you killed and back away from those situations. You need to learn how to play from behind and stay under towers when you're losing lane, so you can farm enough to get back into the game, and so your lane opponent doesn't pump himself up by stomping your face and then steamroll your team. Don't go into fights unless you are pretty sure you can win.
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You have not been upgrading your boots until late in the game. Most players get their boots much sooner. If they can move faster than you, you can't reposition effectively in teamfights, and you can't get away and survive if a battle breaks badly for you.
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You have not been buying a sightstone. Whichever team has vision gets to choose when a lot of fights happen. If you and your ADC can see when the enemy jungler tries to steal your red when you're losing lane, or tries to take his own blue when you're winning, then you can go kill him while he's at the camp. If you see the midlaner moving down the river, you can meet up with your jungler and kill him before he comes in and ganks your lane.
In lower tiers, you won't get your teammates to buy many pinks, so the burden of providing vision falls on you. You need those wards. Buy a sightstone. Also, buying a sightstone lets you take a red trinket and clear enemy vision, which provides an additional tactical advantage.
