While everyone will deny it (Rioters included), there is a very large chance key shards are bugged actually.
The way the system has it right now, you're supposed to be getting about 12 key shards each month (enough to open the chests you can earn each month) before a reset happens next month. And this is regardless of PvP play time. The way it is, you're meant to basically get your first few after your first win or two.
Riot has such things like;
http://na.leagueoflegends.com/en/news/community/q/ask-riot-haz-keys-no-haz-bugs-please
https://support.riotgames.com/hc/en-us/articles/207884233-Hextech-Crafting-Guide
These back up that claim on how key shards are supposed to work.
However though, you have plenty of players such as you and I who have gone months without earning a single key shard regardless of how many PvP games we've won.
The problem is though, bringing up your lack of key shards, people will just give you crap for saying it's bugged and Riot will completely ignore you if you send in a support ticket about the problem. (Personal experience on those; Rioters actually copy and pasted their responses from those two links I put earlier in the support ticket.)
Eventually it got to the point where the problem actually just fixed itself and a reset finally happened on my account this month. The irony of the matter is though that there was only 1 day of this month where I earned 6 key shards.
And I'll admit, 6 key shards is nice, I was able to open a whole 2 out of my 7 chests; but regardless of how amazing my 1 day of key shards was, clearly that is not how the system is supposed to work.
So lastly here then, my only real advice to you is to just keep playing like normal and hope your account fixes finally. I went 3 months without key shards (and hadn't even been playing for two months prior to that) before I finally got my 1 day of key shards.
Hopefully Rito will actually, you know, listen to their fan base for once and not their wallets and actually look into Hextech Crafting. Too often you hear of players mentioning going months without key shards; Hextech Crafting is meant to be presented as a "free rewards system", yet it doesn't work properly until you put money into it.
