Everyone has bad streaks, looking at your recent matches on lolking though, you're dying too often.
Looking at your runes and masteries: Runes, you pretty much need the armor/mr setup you have on every rune page, not just your active one. Your other ones that don't have magic resist, means their ap is practically doing pure damage on you, and you're mainly playing support, so you're basically getting melted. Masteries: I think you should focus more on the defense tree for now, get the veteran's scars, etc. You need the extra health since you're feeding practically every game.
Which leads to the other thing, your positioning must not be great if you're dying as often as you are. You either need more wards and better map awareness so you can avoid ganks more often, or you're positioning yourself poorly in lane. Try to get a better feel of when to engage and when not to.
I'd even recommend buying health crystal sooner. It might not be the most efficient path but probably second item for you after philo stone should be health crystal, you need to stay alive more.
And your ap mid where you went void staff first item ... check some guides out. Get a doran's ring or something.
Once you get better you can build more optimally but for now buy health while you're learning to position yourself better.