Well for one, you upgraded your support item. People in Silver ELO aren't skilled enough to make it necessary for you to actually build a support item all the way. It doesn't make much of a difference either way but I find it a waste of time. This is especially true if you are using a bursty support like annie. Your damage even as a support is extremely relevant. The extra little trickle of gold and meagre active on that support item is pathetic compared to the extra burst you could have from building a Lugen's Echo or Rabadon's Deathcap. Don't get me wrong; I'm not asking you to be the main damage dealer. I'm saying that every bit of damage counts and since you have high burst potential, it is better to build bursty. The faster they go down, the better. Of course, it is also situational but at lower tier games, the situations aren't always so item oriented (that's not to say situational gearing is irrelevant; it's just less of an issue).
Two, you are supporting. The easiest way out is to carry yourself out because if you are consistently good at carrying, it is more likely that you will get consistent end game results (victories) whereas if you are consistently good at supporting, it is strongly dependent on you getting consistently good teammate(s), particularly adc.
Three, Your zed was a baddie. Nothing you could have done there.
Four, in your second game, clearly your team was useless/unskilled when compared to your enemy team. These things happen. For many of us, it will likely take one or two seasons of play before we reach Gold (I was silver throughout my first season of play and got Gold on my second season). Basically, my point is just hang in there.