Hextech crafting - Key fragments drop

Hello , i have played about 3 to 5 days to get all of my 4 starting chests and 12 key fragments and since then i havent got a single key fragment even tho i got two chests. My qustion is : is it even possible to earn any more key fragments for the current month/before the monthly reset after earning your 12 key fragments ? i have played over 150 games after i got my 12th fragment and i havent found more.