About chest earning system

Ok, so, I got 7S's with many champions for the past month, I only earned 1 last month. Also, it has been 17 days since I got a chest. I have chest available still but when I earned 3S's in a row for a match, I still got nothing for the past 17 days, has anyone experience this? or is this a bug? In the following page that I linked. It says the following:

"Craft, earn, or purchase content like champions, skins, ward skins and summoner icons in new loot chests you earn by performing well across a variety of champions or as part of a premade. When you or someone in your premade party earns any S rank, you’ll acquire a chest. You can earn up to four chests each month, and each champion you play can earn you one chest per season. Each time you win any matchmade game, there’s a chance you’ll earn a key and winning with friends increases the chance of a key drop. Generally, you can expect to earn a few keys each month. For those who just want to pick up content at a significant discount, we’re offering chests and keys individually in the store. All chests contain random loot worth more than the cost of the chest (well, depending on how you feel about Teemo) so you can purchase with the confidence of knowing you’re getting a good deal (but a direct purchase from the store will still be the best way to pick up specific items). We’ve been testing Hextech Crafting and loot for over a month, and we’re excited to bring the system live around the world. We’ll be rolling out Hextech Crafting to each region throughout the next few weeks, starting with NA (Turkey has already been live for the beta test). While this is the official launch, as with any part of League, Hextech Crafting and loot will continue to evolve (including tuning drop rates and the loot mix of each chest)" Please tell me if there is a fix to this, thanks in advance!![slayer-pantheon-thumbs]