1 Day XP Boost bug

I purchased a 1 day xp boost yet after my first game I am no longer getting more xp. My first game with the boost I got 286xp going 2/2/0 as kaisa with 10 cs on twisted treeline. My next game I played gp going 2/3 with 28 cs and only getting 94xp on twisted treeline. Again the next one was kaisa going 1/0/4 with 29 cs and only getting 89xp on twisted treeline. I don't necessarily know if this is a bug on how I got so much xp the first time and I was only meant to get 100 with the boost or something like that?